MIAMI — The Phillies spotted Zack Wheeler a three-run lead before he threw his first pitch Sunday afternoon at loanDepot park.

Hundreds of Phils fans sitting behind the visitors’ dugout likely figured the rest of the day would be a cakewalk, as did, surely, everybody watching on TV and listening on the radio back home. The Marlins (11-31) are one of baseball’s worst teams, with one of baseball’s worst offenses. Wheeler, meanwhile, has been one of baseball’s best pitchers this year.

But Wheeler struggled in a 10-inning 7-6 loss. He allowed six runs on six hits (one homer) and three walks over four innings. He struck out just two, he threw a wild pitch and he hit a batter on a 0-2 curveball.

It was surprising to watch. So what happened?

“I don’t know,” Wheeler said. “They were just being really aggressive today. I just wasn’t commanding the ball like I wanted to. They got me. I just had an off day.”

Games like this happen, even to pitchers like Wheeler.

“Nothing felt out of whack,” Wheeler said. “I had a hard time trying to fix it just because I didn’t feel anything. Most of the time when you’re doing that kind of stuff, you feel something. You’re pulling off or something like that. You can try to make the adjustment. But I felt great today. [I was] just barely missing. I was frustrated when I was out there, but I think most of the balls were off.”

Wheeler labored through a 30-pitch second inning, in which he walked two batters and allowed one run. After a walk to Josh Bell and a ground-rule double to Jesus Sánchez, Wheeler shook off Phillies catcher Garrett Stubbs a few times during an at-bat with Nick Gordon.

So Stubbs went to the mound to talk to him.

Stubbs was behind the plate Sunday because J.T. Realmuto has a sore right knee. It is not believed to be serious — he could have played in an emergency, Phillies manager Rob Thomson said — but the Phillies want to be cautious with their star catcher.

Stubbs had not caught Wheeler since last season, and even then only twice. On Sunday, he and Wheeler had trouble getting on the same page.

“I throw to J.T. all the time, but it’s not the end of the world,” Wheeler said. “[Stubbs and I] were both on the same page for the most part. It’s just different scenarios where I like to do certain things and he’s just not used to it. This isn’t on Stubby at all. It’s on me. I threw a lot of balls — what, three or four walks? That’s just on me.”

Marlins left-hander Braxton Garrett needed only eight pitches to retire the Phillies in the third, sending Wheeler back to the mound so shortly after he just gotten off the field.

It wasn’t ideal.

“I don’t want these guys to change from their game plan,” Wheeler said. “But, yeah, when it’s a little hot and humid and you really aren’t used to it, it comes up pretty quick. But I don’t want them to change what they’re doing. It’s up to me to deal with it to get back out there, throw strikes and get outs.”

The Marlins had two on and one out in the third when Wheeler threw Josh Bell a 3-2 cutter. Bell sent the pitch to center field for a three-run homer to give the Marlins a 4-3 lead.

It was Bell’s fourth career homer against Wheeler. Only Cody Bellinger (five) has hit more against him.

“He’s got me,” Wheeler said. “I’ve thrown the toolbox at him. He’s one of those guys for me.”

As soon as the ball landed over the wall, Wheeler walked to home plate to chat with home plate umpire Jeremy Riggs. Wheeler wondered about a 2-1 pitch to Bell that appeared to be a strike, but was called a ball.

It was a quick conversation. It was calm.

“I just had a couple questions for him,” Wheeler said. “We’re not trying to fight out there.”

The Phillies tied the game in the sixth, but they could not deliver the big hit late. Gregory Soto started the 10th. Emmanuel Rivera hit a ball up the middle. It deflected off Soto’s rear end and scooted into the outfield to score the winning run.