The Giants took care of business during their most recent homestand, winning five of six games against the sub-.500 D-backs and Mariners to continue their push for a postseason berth. They arrived in San Diego on Thursday to face a much bigger test in the Padres, who rank second in the National League in winning percentage and are making a serious bid to dethrone the Dodgers in the NL West.

But the Giants couldn’t measure up to the NL heavyweights, as they dropped both ends of a doubleheader Sunday afternoon to seal a three-game sweep at the hands of the Padres at Petco Park.

The Giants broke through with an RBI double by Mike Yastrzemski in a 3-1 loss in Game 2. But that was pretty much it. They cobbled together only five hits over 14 innings, an uncharacteristically quiet showing for their relentless offense. Mike Clevinger pitched a 6-0 shutout in Game 1.

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The Giants (23-24) fell one game below .500 with 13 games left to play, though they continue to hold the eighth and final playoff spot in the NL. The new seven-inning doubleheader format has not been kind to San Francisco, which is 0-4 with one run on 11 hits in two twin bills against the Dodgers and Padres this year. 

“It’s a tough ballclub over there,” third baseman Evan Longoria said. “No matter if you have to play them in nine-inning games in the regular format or in two sevens. We just have to find a way as a group to get back on track offensively, obviously. Get back to what we have been doing and get back to winning.”

The losses capped a difficult weekend for the Giants, who experienced an unexpected break in their schedule on Friday and Saturday after Alex Dickerson produced a false-positive COVID-19 test that led to two postponed games and caused undue stress for the 30-year-old outfielder and his pregnant wife, Jennifer.

More unsettling news arrived on Sunday morning, when the Giants were forced to place reliever Trevor Gott on the injured list and scratch right-hander Kevin Gausman from his Game 2 start with elbow tightness. Gausman, who has served as a pillar atop the club’s rotation alongside Johnny Cueto, is scheduled to undergo an MRI exam on Monday.

“I have concerns,” manager Gabe Kapler said. “We have one of our best starting pitchers getting an MRI on his elbow. Anytime that happens, there’s reason to be concerned.”

Rookie Logan Webb started in Gausman’s place in the nightcap. The 23-year-old right-hander held the Padres to a home run by Wil Myers over four innings and departed with the game tied, 1-1. It was a step forward for Webb, who had allowed at least four runs in each of his previous three outings.

Webb threw only 66 pitches before Kapler decided to turn the game over to his bullpen. He summoned left-hander Sam Selman to start the fifth, but Selman issued back-to-back walks to Jake Cronenworth and Jason Castro to put a pair of runners on with no outs.

Jurickson Profar followed with a grounder that deflected off the glove of Longoria at third base and bounced into shallow left field for an RBI single that put the Padres ahead, 2-1. Manny Machado later added an insurance run with an RBI single off Tyler Rogers.

Webb said he has been working on a minor mechanical tweak in between starts to make his arm path more efficient and help him fill up the strike zone more consistently. He was prepared to potentially pitch out of the bullpen on Sunday until Gausman’s elbow flared up and prompted the Giants to alter their rotation plans.

Losing Gausman would be a major blow for the Giants, but Kapler said he believes Webb has the potential to continue to build off his performance and deliver quality starts for the club down the stretch.

“We have a lot of confidence in Webb each time he goes out,” Kapler said. “We’re always feeling like he’s about to turn the corner. He’s done a nice job. He hasn’t turned the corner that we know he has in him, which is a guy who can attack the zone with three pitches: a nasty sinker, a sweeping breaking ball and a high quality changeup. …

“Today was promising. We obviously hope that Gaus will be prepared to make his next start whenever we decide that’s going to be. If not, we have a lot of confidence in Logan Webb.”

The Giants will now attempt to regroup on with an off-day Monday before opening a two-game series against the Mariners in Seattle on Tuesday. Despite losing three in a row, the Giants continue to hold a 1 1/2-game lead over the Rockies and Brewers for the second and final NL Wild Card spot, with FanGraphs pegging their playoff odds at 57.8 percent.

“We’re still right there where we need to be,” Kapler said. “We’ve got the Mariners coming up. We need to be prepared for them. I expect us to bounce back well, as we have all season from periods of play that isn’t our best. We’ve been able to be resilient and be tough in those times so far this season. I see no reason why we won’t be going forward. We’ll be prepared coming out of the off day.”