SAN DIEGO -- A few hours before Kyle Schwarber hit an opposite-field, three-run go-ahead home run in an 8-5 victory over the Padres on Sunday afternoon at Petco Park, he assessed the Phillies’ plight following the awful news that Bryce Harper broke his left thumb.

Harper could miss weeks. Maybe months.

Nobody will know until he visits a hand specialist as early as Monday in Philadelphia.

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“There’s no reason to chalk up a season,” Schwarber said. “I don’t want people to get down on themselves. Don’t get me wrong: This is a massive blow. It hurts everyone, but I feel like we’ve got a good team and we still have a chance to compete.

“Is it going to be harder? Absolutely. Absolutely. But Thomper [interim manager Rob Thomson] said last night the sun is going to come up tomorrow. We have to do it.”

It is an immense challenge trying to replace the reigning NL MVP, but the Phillies are far from doomed. They need only to look around baseball and see other teams finding ways to win without their stars. The Padres are without Fernando Tatis Jr. and Manny Machado. The Mets are without Jacob deGrom and Max Scherzer. The Dodgers are without Mookie Betts. The Braves won the World Series last year without Ronald Acuña Jr., who suffered a season-ending knee injury in July.

Thomson recalled Derek Jeter separating his shoulder on Opening Day 2003. The Yankees called up Erick Almonte to take his place. The Yankees went 25-11 until Jeter returned.

“It’s going to be on us to see this thing through,” Schwarber said. “I don’t know the extent of the injury, but if we can get to that point where he’s coming back and [Jean Segura] is coming back, it’s going to be like two massive free-agent acquisitions. If we can just keep taking care of business -- the starters are doing fantastic, the bullpen is doing great and our lineup is still constructed to score runs.

“It’s not like we’re looking for a story, but I think it’s that little extra … we want to do it for another one of our guys that got hurt. We want to do it for him, too.”

The Phillies have stepped up in the 14 innings since Harper broke his thumb. They turned a scoreless tie Saturday night into a 4-2 victory. Several more people stepped up Sunday. Kyle Gibson put the Phillies in an early 5-2 hole, but Nick Nelson pitched 3 1/3 scoreless innings to give the offense a shot to come back.

Nick Castellanos’ two-out single in the fifth scored Rhys Hoskins to make it 5-3. Castellanos said Saturday night that “there’s a way better version of myself.”

He finished with a season-high four hits.

Bryson Stott and Matt Vierling are two of the team’s young players whom Thomson is trusting at the bottom of the lineup. Each reached base to start the seventh inning, setting up Schwarber’s three-run homer to left.

It was Schwarber’s 21st homer of the season.

Corey Knebel pitched a scoreless seventh. He has allowed only one base runner in his last three appearances. San Diego native Garrett Stubbs struck out in his first three plate appearances, but he singled in the eighth to drive in an insurance run. José Alvarado pitched a scoreless eighth. He has not allowed an earned run in his last six appearances.

Thomson asked another San Diego native, Andrew Bellatti, to pitch the ninth because Seranthony Domínguez and Brad Hand were unavailable after pitching or warming up in each of the previous four days. Bellatti signed a Minor League deal with the Phillies in November. Nobody outside the organization knew much about him, but he has been a nice find. He pitched a perfect ninth to pick up his first career save.

Bellatti got the ball from the final out and handed it to his father.

“The guy has been elite,” Knebel said. “He’s on another level right now. He’s got the ‘it’ factor. He comes in, and he knows that there’s no one better than him out there. And that’s what you’ve got to do.”

That’s what the Phillies will need to do, regardless of the results of Harper’s test this week. They will need to find a way to win.

“It’s a good team,” Schwarber said after the game. “It’s a really good team. … I don’t think there’s going to be any doubt in our head when we’re stepping out onto that baseball field.”