Kyle Shanahan, head coach of the San Francisco 49ers, wanted to draw a line between toughness and improper acts for his players during training after the team's practice was halted again due to a brawl on Tuesday.

Star middle linebacker Fred Warner and receiver Brandon Aiyuk of the 49ers traded punches on Tuesday. The two already had a brush when Aiyuk told reporters that Warner was "annoying" and it was "irritating" for him to continue to rip the ball and touch teammates even after the plays were over.

Warner soon replied to Aiyuk's comments. "Specifically with Brandon, I chose him out," he said. "I think he's ready to make that next step into playing at an elite level. I've gotten after him a little bit ... because I know how much he has in him. And I know if I nag him a little bit, he's going to get sick and tired of that and start to hold his own. ... He's started to really gain that mindset of knowing he's a guy and he's capable. I'm trying to get the best out of him. That's it."

During Tuesday's practice, Warner hit receiver Marcus Johnson and put him in the concussion protocol as a result. That's how the fight between Warner and Aiyuk happened, among other conflicts within the team.

"I love the intensity of it," Shanahan said on Friday. "I don't think you have to fight to be intense, though. Scuffles are scuffles but then they lead to other stuff. I think that's why we've got a guy in protocol because he took an unnecessary shot on someone which led to the big fight and then we had a bunch of haymakers and stuff thrown in there, which only break hands."

Tuesday's practice continued after the fights without new incidents. Everything went smoothly on Wednesday as well.

"I think our team is pretty tough," Shanahan said. "I think we're pretty physical. I think it most probably voted on who would be the most physical team on tape last year, I think we'd win most of that, and we didn't get in one fight last year. So, I don't think that totally pertains to toughness."

"Once you throw a punch, you get ejected or you get a penalty, and we pride ourselves on, I want people to be irritants, I want people to get as close as they can to all that stuff. I want people to get right on the line where they're about to black out, but you can't black out on the football field or you cost your team," he added.

The 49ers were 10-7 and third in the National Football Conference (NFC) West last season. Though they were not the most favorable team, the franchise knocked out the Dallas Cowboys and Green Bay Packers in the postseason to reach the NFC Championship Game in which they lost to the Los Angeles Rams.

During this offseason, the 49ers allowed their quarterback (QB) Jimmy Garoppolo to look for a destination to join. They are likely to make Trey Lance, whom they drafted with the third pick in 2021, the new starting QB for the 2022 season.

"That's why we looked into trading Jimmy, because we obviously believe that Trey can be a starter and we're ready to do that," Shanahan said in late March.