The San Francisco Giants look to Madison Bumgarner on Friday afternoon in an effort to stretch their winning streak to four straight games. The left-hander takes the hill for the opener of a three-game series with the Chicago Cubs.

Bumgarner is 14-8 with a 2.93 earned run average in 26 starts this season and that includes a dominating effort against the Cubs back on June 1. He yielded two runs over eight innings, striking out 11 without a walk.

The 23-year-old's control wasn't as sharp last time out on Saturday against the Atlanta Braves. After giving up a run and striking out 16 over 17 frames in back-to-back wins, Bumgarner was charged with four runs on seven hits and four walks with five strikeouts over 6 1/3 frames of a loss.

The four runs were the most he had given up in nine starts and he also matched a season high for walks in an outing.

"I felt pretty good the first couple innings, and then the wheels kind of fell off for me," Bumgarner said. "I was able to battle through it and get some outs, but you can't pitch that way, not feeling confident with your stuff and not being able to put the ball where you want to."

Bumgarner looks to rebound against a Cubs team in which he owns a lifetime mark of 3-1 with a 2.08 ERA in five meetings.

The Giants have won eight of their last 10 to open up a 4 1/2-game edge over the Los Angeles Dodgers for first place in the NL West. They are coming off a three-game sweep of the Houston Astros, rallying from an early four-run deficit to claim an 8-4 victory in Thursday's finale.

Pablo Sandoval and Hunter Pence each drove in two runs and Brandon Belt had four hits with an RBI.

Ryan Vogelsong won his second straight start as he gave up four runs on seven hits with a walk and seven strikeouts over six innings. He also had a hit and scored a run.

San Francisco hopes to prevent Chicago starter Chris Volstad from building a winning streak today.

Volstad is coming off his first victory since July 10, 2011 as he beat the Colorado Rockies on Sunday to snap a 24-outing winless streak. He was 0-14 with a 5.54 ERA over the skid before holding the Rockies to three hits and three walks over 6 2/3 scoreless innings.

The 25-year-old had to wait out a 2-hour, 23-minute rain delay before getting a chance at the win.

"It's only fitting that the day took pretty long," said Volstad, who improved to 1-9 with a 6.28 ERA in 14 starts this season.

The righty is 1-2 with a 2.67 ERA in four career starts versus the Giants and aims to win two straight starts overall for the first time since June 25-30 of last year.

Chicago appeared to be on its way to a ninth straight loss to the Milwaukee Brewers on Thursday, trailing 9-3 before the bottom of the sixth. However, the Cubs tied the game in the frame, and after falling behind again, rallied for three runs in the ninth for a 12-11 triumph.

Alfonso Soriano had the game-winning hit, a single that plated Starlin Castro and gave the Cubs just their seventh victory in 28 contests in August.

"It really got ugly there. I wasn't the happiest guy in the world in about the fifth inning," Cubs manager Dale Sveum admitted. "It was nice to see every body, from the guys on the bench battle back and obviously win it."

After snapping their slide to the Brewers, the Cubs will try to avoid a sixth straight loss to the Giants. That includes a four-game sweep by San Francisco at home from June 1-4.