Jason Vosler found himself filling in for not one, but two injured first basemen on Wednesday.

Before the game, Vosler was called up from Triple-A Sacramento to replace Brandon Belt, who landed on the injured list with a mild left oblique strain. Hours later, Vosler was thrust into action when Darin Ruf was forced to exit in the sixth inning with a right hamstring strain.

Vosler responded by picking up the Giants in a huge way, crushing his first career Major League home run to lift the club to a 5-4 comeback win over the D-backs, which clinched a sweep of this two-game series at Chase Field.

• Box score

“I would be lying if I really told you that I remembered all of it,” Vosler said. “It’s kind of a blur right now. I remember going up to the at-bat, I remember the approach through the at-bat, but once I hit the ball, I don't remember much until I was out in the field the next inning.”

The Giants trailed, 4-0, after two innings, but they halved the deficit by scoring a pair of runs in the sixth and then went ahead after Austin Slater and Vosler launched back-to-back home runs off Arizona left-hander Alex Young in the eighth.

Slater, who came off the bench to hit for Alex Dickerson, tied the game at 4 by walloping a mammoth shot into the second deck in left field for his sixth home run of the year. Slater’s third career pinch-hit homer rocketed off his bat at 109.1 mph and traveled an estimated 460 feet, according to Statcast.

“That one felt pretty good off the bat,” said Slater, who punctuated the moment with a bat flip. “You could say a no-doubter, I think.”

That brought up Vosler, who won the left-on-left matchup by depositing a 3-2 fastball over the right-field wall and safely into the glove of Jake McGee in the Giants’ bullpen.

“That’s probably the clutchest first homer I’ve seen,” Slater said.

Vosler, who entered Wednesday 2-for-14 over his first eight games in the Majors, said he blacked out while rounding the bases, and the Giants’ dugout entered into a similar state of delirium. Manager Gabe Kapler was standing next to Evan Longoria in the dugout when Vosler went deep and said he couldn’t remember the last time he saw Longoria that excited.

“When one of our players goes down and has to come out of the game, it's really, really gratifying to see another player step up and get a big hit,” Kapler said.

Drama mounted after the D-backs loaded the bases with one out in the bottom of the ninth, but Tyler Rogers struck out Ketel Marte and retired Eduardo Escobar on a groundout to seal the win for the Giants (30-19), who moved into a tie with the Dodgers for second place in the National League West. The Giants will head to Los Angeles to kick off a four-game series at Dodger Stadium on Thursday.

Vosler’s game-winning shot helped ameliorate some of the sting of losing Ruf, who was set to become the Giants’ primary first baseman while Belt was out. Ruf batted cleanup on Wednesday and went 2-for-3 with a pair of singles before sustaining the untimely injury in the sixth.

After lining a base hit to left field, Ruf rounded first base, pulled up hard and then immediately grabbed his right hamstring, his face contorted in pain. Ruf slammed his helmet on the ground in frustration before walking off the field and returning to the dugout, where he slammed it again.

“The main frustration was knowing that I was going to be able to get some time at first with Brandon's unfortunate side injury,” Ruf said. “We can't help the timing on these things, but it was definitely frustrating knowing that I was going to hopefully be able to be in there more often and help the team.”

Ruf said he is expecting to undergo an MRI exam on Thursday in Los Angeles to determine the severity of the injury. If Ruf needs to miss time, the Giants could turn to Vosler or LaMonte Wade Jr., who filled in for Belt at first during the club’s series in Pittsburgh earlier this month.

The Giants have been hit hard by soft tissue injuries this season, as two other first-base options -- Tommy La Stella and Wilmer Flores -- also hit the IL after tweaking their hamstrings while running the bases. La Stella is expected to be out until at least the first week of July, though Flores could return once he’s eligible on Saturday in Los Angeles.

• Injury updates

The Giants will also receive reinforcements in their starting rotation, as Logan Webb is expected to come off the IL and pitch on Saturday after missing one start with a right shoulder strain. Alex Wood, Anthony DeSclafani, Webb and Kevin Gausman will start in that order against the Dodgers as the Giants look to avenge the three-game sweep they suffered at the hands of their longtime rivals at Oracle Park last weekend.

"I think we have a team that knows how to pick each other up," Kapler said. "Ruf is a big loss for us and obviously with Belt having just gone on the IL, it makes it even more significant. I don't want to discount that. At the same time, we have to turn the page and get ready to play tomorrow's baseball game with the roster that we have. Right now, it's an exciting opportunity for Vosler and for others, so that's what we'll be doing. We'll be getting those other players ready to perform and step in and do good work."