Colorado @ San Francisco preview

Last Meeting ( Sep 19, 2012 ) Colorado 1, San Francisco 7

The San Francisco Giants, whose magic number to clinch the National League West is five, will try for their sixth straight victory over Colorado when they host the Rockies on Thursday in the season series finale. The Giants, who have a nine-game lead on the Los Angeles Dodgers, are 13-4 against the Rockies in 2012 and have won 10 of the last 12 meetings. San Francisco will send Barry Zito to the mound. He is 4-0 in his last eight starts - all Giants' victories. Colorado is struggling to the finish line. The Rockies (58-90) have lost 12 of their last 14 games overall and on the road, and need to win nine of their last 14 games to avoid setting a club record for losses.

Colorado's Jorge De La Rosa will make his his first start since undergoing Tommy John surgery June 3, 2011. His rehabilitation was twice halted - once by tightness in his left forearm and and then by fluid in his left elbow - before he resumed Sept. 5. De La Rosa, who is 7-2 with a 2.91 ERA in 14 appearances (11 starts) against San Francisco, is expected to be on a 75-pitch count Thursday.

TV: 3:45 p.m. ET, Root Sports (Colorado), CS Bay Area (San Francisco)

PITCHING MATCHUP: Rockies LH Jorge De La Rosa (NR) vs. Giants LH Barry Zito (12-8, 4.21)

De La Rosa was 5-2 with a 3.51 ERA when he left his start May 24, 2011 against Arizona in the third inning. The elbow injury was a huge blow to the Rockies, who were counting on De La Rosa to be a mainstay in their starting rotation. He was 16-9 in 2009 before sliding back to 8-7 in 2010. De LaRosa has made three rehab starts leading up to Thursday. In his final tuneup Saturday, he allowed three runs, six hits, walked one, struck out six and threw 71 pitches in five innings for Class A Modesto.

Zito has yielded one run and 10 hits in 13 innings covering his last two starts, both victories. He hasn't lost since Aug. 2, a 9-1 setback to the New York Mets. He is 6-2 with a 2.59 ERA in 19 games (17 starts) against the Rockies, including a four-hit shutout at Coors Field on April 9. Zito got a no-decision when he yielded four runs and seven hits in 5 1/3 in San Francisco's 9-6 victory over Colorado on Aug. 12. The Rockies' roster is hitting .223 against Zito, with only Carlos Gonzalez (8-for-26, homer, five RBIs) having solid numbers.

WALK-OFFS

1. Gonzalez (left hamstring) returned to the lineup Wednesday and went 0-for-4. He didn't play Tuesday and was limited to a pinch-hitting role Monday.

2. Giants INF Marco Scutaro, who was acquired from Colorado on July 27, is 13-for-27 (.481) against his former team and is hitting .353 with 32 RBIs in 50 games since joining San Francisco.

3. San Francisco was 13-5 against Colorado in 2011.