Oakland A's designated hitter Billy Butler suffered a concussion in a fight with teammate Danny Valencia on Friday after the third baseman punched him in the temple, according to a San Francisco Chronicle report.

While details of the fight have not been revealed publicly, the Chronicle reported Monday, citing multiple sources who were present, that it began before batting practice over what Butler apparently said to Valencia while an equipment representative was in the clubhouse.

According to the Chronicle, Butler had interrupted Valencia's conversation with the equipment rep to say Valencia regularly uses spikes that are in breach of his contract, adding that the rep's company should terminate Valencia's endorsement deal.

"Don't you ever loud-talk me in front of a rep," Valencia said to Butler after the equipment representative had left, before walking swiftly toward him, according to the Chronicle report. "That was wrong."

"I can say whatever I want, and your bitch ass isn't going to do anything about it," Butler reportedly replied.

Billy Butler was placed on the seven-day concussion disabled list Monday after missing two games with what manager Bob Melvin said was nausea and vomiting. Jason Miller/Getty Images

Valencia punched Butler in the head before the brief fight that followed was broken up, the Chronicle reported.

Butler and Valencia have been fined an undisclosed amount by the team, and Butler was placed on the seven-day concussion disabled list Monday. Butler missed Oakland's games Saturday and Sunday with what manager Bob Melvin said was nausea and vomiting.

According to the Chronicle, Butler and Valencia have yet to speak to each other since the incident.

"I have respect for him," Valencia said Monday. "I hope he has respect for me."

A's general manager David Forst said he wasn't concerned with the situation.

"There was an altercation in the clubhouse, we're aware of it, both players have been disciplined and fined and we're moving past it," Forst said. "That's it. From the organization's standpoint, it's resolved and we're moving past it."

Catcher Stephen Vogt said "this happens in every clubhouse in America."

Butler and Valencia have been teammates in both Kansas City and Oakland in parts of 2014 and 2015 and all of 2016.

Valencia has had the better season of the two, batting .302 with 15 homers in 97 games, while Butler in 79 games is batting .286 with four home runs.

Forst said Oakland -- among the worst teams in the American League -- would not suspend the players.

"This is not the first time guys have gotten into a fight in the clubhouse," Forst said. "Unfortunately, when you're having the kind of season that we're having, it's a big story. If we were winning, it would be colorful, but we're not."

Forst was asked if he considered it colorful for one player to injure another. He quietly replied, "I don't know."

Butler was seen by the A's medical staff over the weekend but was not in the clubhouse when Oakland began a three-game homestand with the Indians on Monday. Cleveland won 1-0 behind a solo homer by Carlos Santana.

Valencia did not start and struck out as a pinch hitter in the ninth inning.

Melvin addressed the team without Valencia and Butler present on Sunday. Melvin said he stands by the decision to fine and not suspend the players.

"You're not always going to get along great, but I expect us to be fine going forward," Melvin said. "I think this is the easiest way to move forward."

Information from The Associated Press was used in this report.