The San Francisco Giants defeated St. Louis in last year's NLCS en route to another World Series title, and they could use more wins over the Cardinals to boost their chances of making this postseason.

Within striking distance in the NL West and wild card, the Giants are in the midst of a challenging slate that includes six matchups against the team with the best record in the majors. They'll also have to face a likely motivated Michael Wacha in the first of those Monday night.

San Francisco took five games to dispatch St. Louis before claiming its third championship in five seasons but has some work to do to make this year's playoffs. The Giants (64-53) trail the Los Angeles Dodgers by 2 1/2 games in their division and have a 3 1/2-game deficit in the wild card to the Chicago Cubs.

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San Francisco started a 26-game stretch against playoff contenders by losing their slim wild-card lead in a four-game sweep at the Chicago Cubs from Aug. 6-9. The Giants rebounded by going 5-1 at home against AL West-leading Houston and Washington, completing a four-game sweep of the latter with a 5-0 victory Sunday.

"I really thought this homestand was critical for us, coming off a road trip where you get swept in a four-game series," manager Bruce Bochy said. "We really clicked everywhere in this series."

San Francisco will next embark on a seven-game road trip against teams with the NL's best two records, St. Louis (75-42) and Pittsburgh (69-46). The Giants will then return home to face the Cubs and Cardinals, winners in eight of 11.

In its first matchup with St. Louis since the NLCS, San Francisco has the added challenge of taking on a team that's produced one of its best home records in franchise history (44-18). St. Louis will also send out one of the MLB's co-leaders in victories in Wacha (14-4, 2.93 ERA).

The right-hander has allowed two runs in 20 innings while winning his last three starts and outdueled another 14-game winner, Pittsburgh's Gerrit Cole, in a 4-2 victory Wednesday.

He could become the majors' first 15-game winner Monday depending on how Cole performs against Arizona.

Wacha will face the Giants for the first time since giving up Travis Ishikawa's pennant-clinching homer in the ninth inning in Game 5. Wacha pitched six innings in a 2-0 win at Busch Stadium in his only start against San Francisco on May 31, 2014.

Chris Heston (11-7, 3.38) will seek his first victory this month in his first appearance against St. Louis. The right-hander is 0-2 with a 5.40 ERA in his three starts in August, yielding one run over 6 1-3 innings in a 2-0 loss to Houston on Wednesday.

Heston has allowed a combined eight runs in 8 2-3 innings in two road starts this month.

Randal Grichuk's status for St. Louis is unknown because of right elbow tightness, and the outfielder is scheduled to have an MRI on Monday.

"We're not going to get too far ahead of this," manager Mike Matheny said. "We'll let the tests dictate how far we need to look into the future."

Grichuk is batting .324 with eight homers, 20 RBIs and a 1.025 OPS in his last 28 games.