As first revealed by the The Telegraph, the pair clashed a day on from the Blues’ shock 5-2 defeatto West Brom at Stamford Bridge.
The disagreement was sparked by a late tackle by Rudiger on the goalkeeper, who reacted strongly before things escalated into a physical confrontation.
Rudiger was sent away from training early to calm down by bos Thomas Tuchel.
The German defender is understood to have later apologised to Kepa and Tuchel and the club consider the matter now closed.
The news of the altercation will, however, do Tuchel no favours as his side prepare for their Champions League quarter-final clash against Porto on Wednesday.
Tuchel, whose 14-match unbeaten run as Blues boss came to an end with the crushing defeat to struggling West Brom, had warned his players not to ‘lose their heads’following the match.
“We cannot lose our heads now and take away the trust we have in these players,” said Tuchel.
“It was the moment after the game to be honest, be calm and to tell everybody to breathe.
“This will be a hard evening for everybody.
“We had completely different plans how to start this match day so we have to accept it now, it’s our first loss together.
“It’s important to find a way to deal with it together.”
Thiago Silva’s first-half red card altered the complexion of the contest in west London, but after that the Baggies dominated and fired five impressive goals.
And Kurt Zouma insisted Chelsea cannot seek excuses for Saturday’s shock defeat and urged his side to ‘react strongly’.
“The result speaks for itself. Everyone is very disappointed, but it’s just one game and we need to get back to what we were doing before the international break and, hopefully, we will get back to it as soon as possible,” Zouma told Chelsea’s official club website.
“There’s no time to find excuses. We didn’t win the game, we lost badly, and it’s a very difficult game to swallow, but we have to because we’ve got another game in midweek and we have to prepare for that.
“We have to bounce back. We have to react strongly and this is what we are going to do.
“I don’t know what happened. After the international break, maybe a loss of focus, maybe a lack of commitment, but in a game like that you have to always be 100 per cent. Why we didn’t play 100 per cent I don’t know.
“There are days when it’s not your day. Everyone’s very disappointed, there’s not much I can say.
“Maybe we weren’t focused enough, maybe West Brom wanted it more than us, but I don’t think that’s possible. You have days like that where nothing goes your way.
“You have to learn from everything. In football you have to give your all every time on the pitch. We learn there maybe tactically, from mistakes on the ball, without the ball too. We will analyse it calmly and then move on from there.”