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(Sports Network) - Left-hander Jorge De La Rosa returns to a major league mound for the first time in nearly 16 months on Thursday when the Colorado Rockies wrap up a four-game set with the San Francisco Giants at AT&T Park.

De La Rosa, who hasn't pitched since May 24 of last season, missed most of the last two years recovering from Tommy John surgery and his return to the hill was delayed even longer, as he had injury rehab assignments halted because of tightness and swelling in his left elbow.

However, De La Rosa was pain-free and mostly effective in three recent starts, one at Rookie-level Grand Junction and two at Class A Modesto.

"It's really exciting to be back in the game," De La Rosa said. "But at the same time I have to be calm, don't get too excited on the mound. That will be real hard for me, but I will try to stay calm and make my pitches."

De La Rosa, who was 7-2 lifetime versus San Francisco, won a career best 16 games in 2009, but has won just 13 since.

San Francisco, meanwhile, will counter with lefty Barry Zito, who is 4-0 over his last eight starts. Zito won his second straight outing on Saturday in Arizona, as he held the Diamondbacks to a run and six hits in 6 2/3 innings to improve to 12-8, while lowering his ERA to 4.21.

Zito's 12 wins are his most since signing a 7-year, $126 million deal prior to the start of the 2006 campaign. The Giants have also won his last eight starts.

"It's great to be out there and be part of a win, regardless of how you get it," Zito said. "It's not really about personal stats, it's about team stats. Especially (while) making a playoff run."

Zito has faced the Rockies 19 times (17 starts) and is 6-2 against them with a 2.59 ERA.

San Francisco moved one step closer to a National League West crown on Wednesday, as Matt Cain pitched eight solid innings of one-run ball to lead the Giants to a 7-1 win.

Cain (15-5) scattered four hits and fanned eight while walking four to earn his fifth straight positive decision. Jose Mijares finished off the rout with a perfect ninth inning.

Pablo Sandoval popped a three-run home run among his three hits, while Gregor Blanco went 3-for-4 with a two-run single for the Giants, who have won the first three games of this set and lowered their magic number for clinching their second division title in three years to five.

DJ LeMahieu knocked in the lone run with a sacrifice fly for the Rockies, who lost for the fifth consecutive game. Tyler Chatwood (4-5) took the loss after allowing three runs on eight hits in four innings.

The Rockies have lost 13 of 17 to the Giants this season.