The San Francisco Giants used a recent three-game sweep to grab slim control of the NL West, while the Atlanta Braves needed to salvage the finale of their series on Wednesday to avoid falling behind in their chase.

The two clubs now meet on Thursday in San Francisco to begin a four-game series between playoff hopefuls.

The Giants are coming off a three-game sweep of Los Angeles that put them 2 1/2 games ahead of the Dodgers for the division lead. San Francisco completed the crucial sweep with an 8-4 win on Wednesday.

Joaquin Arias started his career-high five RBI game with a two-run homer in the first inning, while Angel Pagan had a pair of hits and scored three times to give San Francisco its eight victory in 11 games.

Matt Cain allowed seven hits and a run over seven innings to win his third straight start and help the Giants to their first sweep of three-or-more games versus the Dodgers since April 24-26, 2007.

"Matt did a great job. He made pitches when he had to. The guys had great focus on defense," Giants manager Bruce Bochy said.

Catcher Buster Posey did not play on Wednesday and is day-to-day due to a tight right hamstring that isn't considered serious.

The Braves went into a three-game series with the NL East-leading Washington Nationals hoping to make up ground, but dropped the first two contests before notching a 5-1 win on Wednesday. That left Atlanta six games off the pace.

Kris Medlen tossed seven scoreless innings, striking out seven as the Braves snapped a four-game slide. Atlanta has won the last 16 games that Medlen has started, dating to May 2010. The streak is the longest in franchise history.

"He's not a big guy, but he walks out there like, 'I know I can get you out.' He's got a few different ways to do it," Braves third baseman Chipper Jones said.

Martin Prado knocked in two runs, while David Ross and Michael Bourn had an RBI apiece.

Tommy Hanson tries to avoid his first loss since July 2 as he goes for the Braves.

Hanson is 3-0 in is last six starts, though that span includes a stint on the 15-day disabled list because of a strained back. He returned from that ailment on Thursday and logged a no-decision versus the Dodgers, allowing three runs over 6 2/3 innings in his first start since July 30.

The 26-year-old righty is 12-5 with a 4.27 earned run average in 23 starts this season. He'll look to stay undefeated versus the Giants in his career, going 2-0 with a 2.14 ERA while fanning 21 over three starts and 21 innings.

The Giants turn to Barry Zito, who has won just once over his last six starts though his club has won his last three appearances. Zito hasn't factored into the decision of his past two starts since a win over the St. Louis Cardinals on Aug. 7.

The 34-year-old southpaw lasted four innings versus the San Diego Padres on Saturday, yielding four runs on six hits with two walks. He is 9-8 with a 2.03 ERA in 24 outings this season.

Zito held the Braves scoreless over seven innings in a July 17 victory, scattering three hits while moving to 4-1 with a 2.03 lifetime in the matchup.

San Francisco won two of three in that set at Atlanta.