By Tony Moss, NFL Editor -- (Sports Network) - When they meet the St. Louis Rams at the Edward Jones Dome on Sunday afternoon, the San Francisco 49ers are bound to feel the weight of heightened expectations.

Whether Mike Nolan's team crumbles under that weight will help determine their fate in 2006.

San Francisco comes into the Gateway City riding a three-game winning streak, the longest for the franchise since 2002. After downing the Vikings (9-3) and Lions (19-13) in succession, the Niners scored their most impressive victory of the season to date last week, jumping out to an early 20-point lead on the reigning NFC Champion Seahawks before holding on for a 20-14 win. The Seattle victory moved San Francisco, a team that had allowed a whopping 235 points during a wretched 2-5 start, within one game of the top spot in the NFC West, and entered the Niners into the playoff discussion for the first time in what seems like ages.

The goal for Nolan and company on Sunday will be to extend the winning streak to four (which would mark the longest run for the organization since it won five in a row in Weeks 8-12 of the 2001 campaign), keeping the heat on the first-place Seahawks (6-4) and making the 49ers' return trip to Seattle on Dec. 14th meaningful.

The team that will try to end San Francisco's streak is currently in free fall. St. Louis has lost five straight since fashioning a 4-1 start, with last Sunday's 15-0 loss at Carolina looking a lot like rock-bottom. The shutout was the first absorbed by the franchise since the 1998 season, and the loss gave the organization its first five-game losing skid since it began the 2002 season at 0-5. Another defeat on Sunday would give the Rams, who have lost three straight games in their series with the 49ers, their first seven-game skein since 1997.

SERIES HISTORY

The Rams hold a 58-53-2 edge in their regular season series with the 49ers, but as mentioned, have lost three straight to San Francisco, including a 20-13 loss at Monster Park in Week 2. St. Louis was also swept in a home-and-home against their division rival last season, dropping a 28-25 road decision in Week 1 and 24-20 road setback at the Edward Jones Dome in Week 16. Prior to last season, St. Louis had won 10 of the last 12 overall, including a home- and-home sweep in 2004.

In addition to the regular season series, the teams have met once in the postseason, with San Francisco earning a 30-3 home triumph over the then-Los Angeles Rams in the 1989 NFC Championship.

Nolan is 3-0 against St. Louis in his career, while the Rams' Scott Linehan is 0-1 against both Nolan and the 49ers as a head coach.

49ERS OFFENSE VS. RAMS DEFENSE

No single player has been more important for the 49ers during their three-game streak than running back Frank Gore (1043 rushing yards, 37 receptions, 6 TD), who rushed for a career-high 212 yards last Sunday and enters Week 12 just two yards behind the Chiefs' Larry Johnson in the race for the NFL rushing title. Gore has torn up the Lions and Seahawks in the first half of each of the team's last two games, going for 148 in the first 30 minutes against the Lions, and for 130 in the initial two quarters against Seattle. The only sticking point for the dazzling second-year runner has been the five fumbles Gore has coughed up on the year, including a potentially costly one late in the fourth quarter against Seattle last week. Backup Maurice Hicks also logged eight touches versus the Seahawks, making his five rushes and three catches count for 36 yards. Rookie short-yardage back Michael Robinson (77 rushing yards, 2 TD) has also been a staple in the lineup.

Gore will likely be foaming at the mouth at the prospect of facing the Rams, who enter Week 12 dead last in the NFL in yards per carry allowed (5.2) and are ahead of only Indianapolis in rushing yards allowed per game (153.2). Seven different running backs have gone over 100 yards against St. Louis, which includes Gore's 127-yard effort back in Week 2. Counted on for more strength at the point of attack will be Rams defensive tackles Jimmy Kennedy (27 tackles) and La'Roi Glover (25 tackles, 3.5 sacks), who were present when four different Panthers running backs combined for 245 ground yards last week. The linebacking corps of Will Witherspoon (82 tackles, 2 sacks) in the middle and Pisa Tinoisamoa (26 tackles, 2 sacks) and Brandon Chillar (32 tackles, 2 sacks) on the outside has also had its problems, though Witherspoon has been something of a tackling machine this year. Witherspoon had eight tackles against the Panthers, and Glover had six stops and two sacks from his spot up front.

Though he hasn't been sensational like his backfield mate Gore, 49ers quarterback Alex Smith (1824 passing yards, 10 TD, 7 INT) has been efficient and largely mistake-free during the team's three-game win streak. The second- year-pro and No. 1 overall pick in the 2005 Draft has completed 33-of-45 passes (73.3 percent) for 299 yards and a touchdown without an interception in his last two games combined, and also rushed for his first score as a pro in last Sunday's win over the Seahawks. Smith has a solid 82.7 passer rating on the year as Week 12 begins. Wideouts Antonio Bryant (31 receptions, 2 TD) and Arnaz Battle (35 receptions, 3 TD) have been two of Smith's favorite targets, with tight end Eric Johnson (29 receptions) remaining healthy enough to make an impact as well. Battle had five catches for 47 yards and his third touchdown catch of the year against Seattle, while Johnson hauled in four- passes for a team-best 48 yards. Bryant will play on Sunday despite his arrest last week on charges of reckless and drunken driving. Rookie tight end and No. 5 overall draft pick Vernon Davis (5 receptions) returned to the lineup last week after missing six games with a broken fibula, but did not have a catch. San Francisco has surrendered a modest 22 sacks on the year, including one last Sunday.

The Rams are a healthy ninth in the league against the pass as Week 12 commences (193.4 yards per game), though the fact that St. Louis has faced the third-fewest passing attempts in the league (279) has something to do with that stat. Cornerbacks Fakhir Brown (35 tackles, 2 INT, 1 sack) and Tye Hill (28 tackles, 2 INT) will likely be matched up with Bryant and Battle this week, with O.J. Atogwe (40 tackles, 2 INT, 1 sack) and Corey Chavous (52 tackles, 1 sack, 1 INT) lending support from their safety slots. The rookie Hill, a first-round draft choice, notched the second interception of his pro career off of Jake Delhomme last Sunday, while second-year-pro Atogwe was credited with four tackles and two forced fumbles in the loss. Linehan's team is middle-of-the-NFL pack with 25 sacks on the year, including a team-best 10 from Leonard Little (38 tackles). Little posted five stops with a sack and a forced fumble in Carolina last week.

RAMS OFFENSE VS. 49ERS DEFENSE

Job number one for St. Louis on Sunday will be keeping quarterback Marc Bulger (2657 passing yards, 13 TD, 3 INT) upright, so that he might be able to look downfield to wideouts Torry Holt (59 receptions, 7 TD) and Isaac Bruce (43 receptions, 1 TD). In his first game without injured Pro Bowl left tackle Orlando Pace (triceps) last week, Bulger was harassed to the tune of seven sacks and completed just 19-of-34 passes for a season-low 142 yards and an interception. Bulger has now been dropped a bloated 35 times on the year, and has been sacked at least twice in each of his past six games. Bulger's two- game streak without a touchdown pass is the longest of his career. Holt and Bruce have felt the offensive strain as well. Holt has seven catches in each of his past two games, but hasn't scored a touchdown in his last four outings after notching seven TDs in the team's first six contests. Bruce was limited to one reception for six yards against the Panthers, his least productive game since the 2001 season. Number three receiver Kevin Curtis (29 receptions, 3 TD) did not have a catch last week, the second time that has occurred this year.

The San Francisco secondary helped fuel the Seattle win by making several plays last week, with cornerback Walt Harris (33 tackles, 6 INT, 1 sack) and strong safety Keith Lewis (25 tackles, 2 INT) doing the most damage to the Seahawks' winning prospects. Harris intercepted two Seneca Wallace passes, giving him an NFL-high-tying six on the year, while Lewis, who was just recently installed in the lineup, intercepted Wallace and recovered a Jerramy Stevens fumble in the win. Elsewhere in the secondary, rookie d-back Marcus Hudson sealed the win by recovering a Mack Strong fumble in the closing seconds. Obviously, the San Francisco secondary will have to be technically sound this week against a pair of legendary wide receivers and a quarterback that rarely makes mistakes. Their job will be easier if a pass rush that has 22 sacks on the year can generate some heat. Linebacker Brandon Moore leads the team with 5.5 sacks, and veteran lineman Bryant Young is second with 3.5.

The Rams will have to get the running game going this week, after the team was basically forced to abandon the ground approach in last Sunday's loss to the Panthers. Running back Steven Jackson (811 rushing yards, 5 TD, 54 receptions) had just seven carries for 27 yards in the defeat, his fewest attempts in a game since midway through his rookie year of 2004. Jackson was a factor in the pass-catching game, however, logging seven catches for 30 yards in the loss. Jackson carried 22 times for 103 yards against the Niners back in Week 2, which marks the former first-round pick's most recent 100-yard game. Ex- Redskin and Panther Stephen Davis (93 rushing yards, 5 receptions) has been an occasional change-of-pace for Jackson, but had just one carry for four yards against his former team last Sunday.

The 49ers are only 15th in the league against the run (113.9 yards per game), but come off a week in which they held reigning NFL MVP running back Shaun Alexander to just 37 yards on 17 carries. Inside linebacker Moore (47 tackles), who was installed in the starting lineup to replace the struggling Jeff Ulbrich just before the team began its three-game win streak, led the Niners with six tackles in the Seattle win. Moore has 31 tackles, 3 sacks, and a forced fumble in his last three games. Three-man line staples Young (31 tackles), Ronald Fields (20 tackles), and Melvin Oliver (24 tackles) were also very good last week. Young and Oliver had five tackles each, while Fields contributed four tackles to the proceedings.

OVERALL ANALYSIS

The lingering skepticism about the staying power of the 49ers in the playoff chase has much to do with their first seven games of the season. It is hard to envision a team that was so bad defensively continuing to ride that side of the ball to victories. The Rams, who have a poor offensive line but plenty of skill players to keep the 49ers guessing, are a good candidate to snap San Francisco back into reality. St. Louis has much to prove after last week's display, is desperate for a victory to end its losing streak, and will remain focused against a team that it has lost to three straight times. Look for the still-green Niners to make a couple of critical mistakes on both sides of the ball, which will help seal their fate.

Sports Network Predicted Outcome: Rams 23, 49ers 16