Antonio Rudiger was dismissed from Chelsea training on Sunday after a fight with goalkeeper Kepa Arrizabalaga, Goal can confirm.
First reported by the Telegraph, Thomas Tuchel sent the German defender back to the dressing room five minutes before the end of the session.
The incident comes a day after the Blues were demolished 5-2 by West Brom at Stamford Bridge.
What happened?
Rudiger and Kepa got into a heated argument and ended up pushing each other as tempers flared on the training pitch.
The centre-back made a late challenge on the goalkeeper during a small-sided game and the latter reacted furiously.
The pair had to be separated by team-mates and Tuchel sent Rudiger away from the pitch to calm down.
How did Rudiger react?
Rudiger later apologised to the Spain international of his own volition.
Chelsea boss Tuchel is said to be satisfied that the issue has been resolved and no further action is expected to be taken by the club.
Tuchel called for calm
The defeat on Saturday is Chelsea's first under their new manager, who urged his players to stay level-headed in the wake of the humiliation.
He told reporters after the match: "It is our first loss together. It is important to find a way to deal with it together, and that everyone knows what I feel as a part of it.
"There were some quick words to calm everybody down and to delay the talks until tomorrow because now it is too emotional, [there] is too much frustration. It is not productive."
What next for Chelsea?
Chelsea are in action again on Wednesday when they face Porto in the first leg of their Champions League quarter-final tie.
They will then face Crystal Palace in the Premier League three days later.