(Sports Network) - The Houston Astros have had to put together a pair of lengthy winning streaks to stay in the National League wild-card race, while the Colorado Rockies are still in the hunt due to a weak NL West.

The Astros and Rockies, both six games back in their respective races, meet tonight at Coors Field in the opener of a three-game series.

Houston has put together its second eight-game winning streak in less than a month to get within six games of Milwaukee for the NL's final playoff spot with 22 to play. The Astros also won a season-high eight in a row from August 7-14.

The Astros enter this series having swept a three-game set against the Chicago Cubs, owners of the best record in the league. In Wednesday's 4-0 victory, Randy Wolf threw his eighth career shutout and first since 2004, while Ty Wigginton hit a two-run homer.

Michael Bourn went 3-for-4 and scored once for Houston, which will try for its first nine-game winning streak since September 20-28, 2006..

Brian Moehler takes the hill for the Astros tonight. After having a five- decision winning streak end with a loss to the Mets on August 25, the righty came back with a win over St. Louis on Saturday. Moehler allowed three runs on seven hits in that one.

The 36-year-old is 10-5 with a 4.02 earned run average in 26 games, including 21 starts, this year. He is also 1-1 with a 6.11 ERA in six games (2 starts) lifetime versus Colorado.

Moehler hasn't started against the Rockies this year, but did face them in relief on April 18. He allowed three runs over three innings on that day.

While Colorado hasn't been nearly as hot as Houston, it still finds itself six games back of first-place Arizona in the NL West despite being nine games under .500 (66-75).

The Rockies were just 32-51 heading into July, but went a combined 32-23 in July and August to creep back into the picture in the division. They took two of three from San Francisco earlier this week, failing to post a sweep after Wednesday's 9-2 loss.

Aaron Cook lasted just three innings in the setback, while Clint Barmes had a solo homer for the Rockies, who have dropped four of their last seven. Jeff Baker drove in a run and Garrett Atkins scored in defeat.

Ubaldo Jimenez gets the nod tonight for the Rockies and suffered through control problems last time out. He faced the Padres on Saturday and allowed six runs on two hits and five walks, dropping to 1-3 with a 7.36 ERA over his last five starts.

The righty is 9-12 with a 4.19 ERA on the season and has walked 87 batters in 167 2/3 innings.

Jimenez, 24, made his first career start against Houston on April 20, getting a no-decision after allowing three runs on five hits and five walks over 5 2/3 innings.

Colorado won two of three when these two clubs met in Houston from April 18-20.