SAN FRANCISCO -- Throngs of partiers and atheletes ran through San Francisco streets Sunday during the annual ING Bay To Breakers -- part Mardi Gras, part road race -- with Kenya's John Korir defending his men's title.

Organizers made a strong effort this year to minimize the waste left behind by revelers, notably those who participate in the annual tortilla war.

The cleanup costs are paid for with the registration fees, which race organizers say weighs heavily on the event’s tight budget. This year, only 33,000 of the estimated 60,000 participants paid to run the race.

As usual, the serious runners set the pace, followed closely by folks in fanciful costumes and, at the back of the pack, an assortment of floats that paused to party in the city’s panhandle district.

Trash, public drunkeness and public urination are big problems each year, and residents here welcomed efforts to push partiers to pick up after themselves.

At the finish line, medical technicians stood alert at the great highway finish line, where a 53-year-old runner last year collapsed and died.

Korir outsprinted Ridouane Harroufi of Morocco over the final 200 meters at San Francisco’s foggy Ocean Beach for the win.

Taking advantage of a break in the triple-digit heat wave that has baked the area for several days, Korir trailed Harroufi over the legendary Hayes Street Hill but took the lead as the runners entered Golden Gate Park.

As they neared the turn into the Ocean Beach, the top men overtook the women’s winner – Kenya’s Lineth Chepkurui – who as part of the women’s elite field was given a 4-minute, 40-second head start over the elite men .

Korir crossed in an unofficial time of 35:24 to claim the $25,000 first prize. Harroufi finished 10 strides behind and Tanzania’s John Yuda was third.

Chepkurui who won the Lilac Bloomsday Run on May 4 took first in a time of 39:22. Her fellow country women Rose Kosgei was second and Jane Kibii was third.

Former Stanford runners Amanda and Katy Trotter were the top American women finishing fourth and fifth.

While the elite runners were finishing up at Ocean Beach, the thousands of recreational runners -- many in wild costumes -- were still crossing the start line in downtown San Francisco.

The annual race is as much a celebration of running as it is a competitive race.