The Reds are upset with Padres slugger Luke Voit for his collision at home plate that left Cincinnati catcher Tyler Stephenson with a concussion on Tuesday night in San Diego.

"The way his hands hit him, it was dirty as f---," Reds outfielder Tommy Pham told reporters. "I don't like it at all. The way [Voit's] hands hit [Stephenson] in the face, it was dirty.

"If Luke wants to settle it, I get down really well. Anything -- Muay Thai, whatever. I've got a [gym] owner here who will let me use his facility."

Voit slammed into Stephenson while trying to score from first on Jurickson Profar's first-inning double. As he went into his slide, Voit raised his arms and then brought them down forcefully into Stephenson's head as he landed.

Stephenson held onto the ball for the out but was on the ground for several minutes. He was able to walk to the dugout but did not return to the game.

"I didn't have a problem with the slide," Reds manager David Bell told reporters. "But it's a helpless feeling when one of your players gets hit in the head and they're lying there. It's scary for me."

The 255-pound Voit said he was trying to avoid Stephenson but admitted his elbow "kind of smoked his head a little bit."

"I wasn't trying to take him out or anything," Voit said. "I guess my elbow just kind of smoked his head a little bit. Hope he's all right, no hard feelings. It's baseball. I wasn't trying to make it dirty or anything. I'm just trying to make a play obviously."

The Reds challenged the call, but umpires ruled Voit's slide was clean.

"It didn't end up hurting us because we didn't need the challenge," Bell said. "I thought it could've been an illegal slide. That doesn't mean that Voit did it intentionally."

"The ball takes him right into Luke," Padres manager Bob Melvin added. "There's nowhere to go, and I think Luke was just trying to protect himself putting his hands up. I think they got it right."

Stephenson's teammates, however, did not agree with the managers.

"Looking back at the replay, I'm not too happy about the slide," Reds shortstop Kyle Farmer said. "Not too often you see a runner slide and grab someone's head and slam it to the ground like that. You're usually trying to reach for the bag. Maybe that's what he was trying to do. After looking at the replay, it looked like a wrestling move to Tyler's head and snapped it down.

"I've caught before, and it's a scary play, especially when you have a big guy like Voit coming down. I've never really seen someone's hands go to a catcher's head on a slide."

Stephenson was placed in the concussion protocol after the game, which will keep him out of the lineup at least seven days. Bell said Stephenson, 25, seemed to be "doing fine" but acknowledged the team was concerned about the third-year catcher.

Pham, a former Padre and a former teammate of Voit's with the St. Louis Cardinals, reiterated his offer to "settle" the situation with Voit at a local gym.

"I don't like it all," Pham said. "They can say what they want. Everybody on that side -- they know I get down. I know a place here, I know an owner who will let me use his gym if we need to settle anything. ... That play was dirty."

The Reds, who have lost eight consecutive games, and Padres will complete their three-game series in San Diego on Wednesday afternoon before meeting again next week for a three-game series in Cincinnati.