Updated

(SportsNetwork.com) - San Francisco's Yusmeiro Petit takes aim at the major league record for batters retired on Thursday when the Giants go after a series win in the finale of their four-game series with the Colorado Rockies at AT&T Park.

The Giants announced earlier in the week that Petit will be taking two-time National League Cy Young winner Tim Lincecum's spot in the rotation. While Lincecum has struggled, Petit has thrived out of the bullpen and enters this contest having retired 38 consecutive batters over his last seven appearances (six relief, one start).

The incredible stretch is just seven shy of Mark Buehrle's major league record set from July 18-28 back in 2009.

Petit has certainly enjoyed more success in the bullpen than in the rotation. In six games as a starter he is just 1-2 with a 6.32 ERA, opposed to a 2-1 mark with a 1.84 ERA in 27 relief appearances.

"I just try to throw strikes and get ahead on the count every time possible," said Petit, who has pitched to a 4.85 ERA in 12 games (6 starts) versus the Rockies. "I'm always ready and prepared for anything that can happen."

Colorado, meanwhile, turns to righty Jordan Lyles, who is riding a seven-game unbeaten streak.

Lyles may not have lost since May 17, but he only has one win since then too. He received another no-decision on Saturday against Miami, as he allowed three runs and seven hits with five walks in 5 2/3 innings of his team's 5-4 win.

Lyles has faced the Giants twice and is 1-0 against them with a 2.70 ERA. This, though, will be his first start at AT&T Park.

He'll have to deal with the red-hot Buster Posey, whose two-run homer with two outs in the ninth inning propelled San Francisco to a 4-2 win on Wednesday.

Tim Hudson followed Madison Bumgarner's gem by throwing eight solid innings for the Giants, but Santiago Casilla (2-3) gave up Justin Morneau's tying RBI double in the ninth.

In the bottom portion, Angel Pagan singled to left off Juan Nicasio (5-6). Hunter Pence struck out swinging on a high pitch for the second out, but Posey homered to left field on an 0-1 pitch to send the Giants to victory.

It was Posey's fifth homer in his last seven games.

"He gave us the hit that we really needed tonight. That would have been a tough one to lose," Giants manager Bruce Bochy said.

Despite losing the last two games of this series, Colorado is 8-6 against San Francisco this season.