SAN FRANCISCO -- Randal Grichuk blasted his 18th home run of the season and Cardinals starter Michael Wacha spun six innings of one-run ball to help St. Louis to a 5-2 victory over the Giants on Thursday night at AT&T Park.
The Giants mustered just one hit against Wacha through the first four innings before piecing together a rally on two hits in the fifth for their lone run. Wacha walked two and struck out two while Grichuk provided a jolt of offense with a two-run shot -- measured at 409 feet by Statcast™ -- in the second inning.
With the win, the Cardinals remained five games back of the Cubs in the National League Central race. They gained ground on the Rockies for the second NL Wild Card spot, moving up to five games out.
"He was great," Cardinals manager Mike Matheny said of Wacha. "[He] got not just his changeup going, but got the curveball going and I thought his cutter was sharp. It seemed like, right out of the gate, he had that down fastball working, and it just kind of locked him in."

Giants starter Player Page for Matt Cain, making a spot start for Madison Bumgarner (flu-like symptoms), pitched a solid game, allowing two runs in five innings on the heels of a rough relief appearance against the D-backs on Sunday. But Cain picked up his career-high 10th consecutive loss. It's the longest losing streak by a pitcher in the Majors since Arizona's Shelby Miller lost 10 straight in 2015.
Cain said the coaching staff gave him a heads up he might start after the Giants' loss to the Padres on Wednesday.
"He gave us all we needed and wanted," Giants manager Bruce Bochy said. "Great job on his part."
Reliever Mark Melancon allowed the Cardinals to tack on two more runs in the eighth, his first blemish since returning from the disabled list. Melancon walked Greg Garcia with the bases loaded and hit Tommy Pham, forcing another run home.

MOMENTS THAT MATTERED
Unearned insurance :The Cardinals tacked on an insurance run in the seventh after an error by Giants second baseman Joe Panik opened the door for a rally. Garcia got aboard with one out and eventually scored when Panik couldn't field a ball in shallow left field. Pham brought him home two batters later with an RBI single to pad the Cardinals' lead with three innings remaining.

Wacha escapes after rally: Wacha escaped the fifth inning allowing just one run after he surrendered consecutive singles to open the frame. The Giants scored a run on pinch-hitter Carlos Moncrief's sacrifice fly after some crafty baserunning by Hunter Pence to cut the lead in half but couldn't capitalize after Denard Span drew a walk to extend the inning. Panik flied out to end the frame.
"That's still a close game at that point, too," Wacha said. "Just trying to grind out there, trying to get out of a jam. Had a little damage control to only give up one, so that was a plus. Always trying to limit the damage, accept those challenges and try and get out of them."

QUOTABLE
"I felt good out there. Was able to establish the fastball on pretty much both sides of the plate. Had a little trouble going glove-side, but for the most part it was pretty good. Was able to throw the offspeed for strikes and get some weak contact, some ground balls. Defense played great behind me." -- Wacha
HOME RUN: OVERTURNED
Brandon Crawford appeared to collect his 13th home run of the season in the ninth inning, but a replay review overturned the shortstop's two-run blast. A review "definitively determined" that a fan interfered with the play, despite evidence that showed the ball was on track to hit the green tin roofing to the right of the "Splash Hits" sign. The official ground rules for AT&T Park demarcate the green metal as home-run territory.
Instead, Crawford was ordered to second with a ground-rule double.
"When you see a fan reach over, it makes it a tough call," Matheny said. "We wanted to make sure they had a good, long look at it at that point. … You just take a chance to see what happens."

The call left the Giants frustrated after the game, though even if it had been ruled a homer, the Giants still would have been down 5-3 with no outs in the ninth, as opposed to 5-2 with a man on second.
"I was told that the fan reached over the fence and that it wouldn't have been a home run," Crawford said. " … For somebody to reach into the field of play in right field, they would have to lay down flat and have somebody hold their feet to make that catch. The guy's glove was easily over the green part there. I thought the only reason it was taking so long is that it was a foul ball."

UPON FURTHER REVIEW
The Cardinals unsuccessfully challenged a base hit by Giants catcher Buster Posey in the sixth. Posey tapped a soft grounder to third and legged out a single after Pablo Sandoval was retired to start the inning. A review determined the play stands.

WHAT'S NEXT
Cardinals: The Cardinals' No. 3 prospect, Jack Flaherty, will make his Major League debut Friday night against the Giants at 9:15 p.m. CT. Rated by MLB Pipeline as the No. 53 prospect in all of baseball, the 21-year-old is 14-4 with a 2.18 ERA in 25 combined starts between Double-A Springfield and Triple-A Memphis.
Giants: After a month and a half on the disabled list, the Giants will welcome back Johnny Cueto (6-7, 4.59 ERA) for Friday's 7:15 p.m. PT contest against the Cardinals. Cueto made two Minor League rehab starts, throwing 72 pitches in his most recent outing, to recover from a mild flexor strain.
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