Antonio Rudiger was shocked to learn the consequences of his bodycheck on Kevin De Bruyne in the Champions League final after the Belgian suffered a broken nose and fractured eye socket.
The German centre-back said he had "been in touch" with De Bruyne since the game, which Chelsea won 1-0 to become European club champions for a second time.
The incident occurred in the 56th minute of Saturday's showpiece in Porto, at which point Pep Guardiola's City side had already conceded what proved to be the decisive goal from Kai Havertz.
De Bruyne watched from the stands for a while before being taken away for checks, and it remains to be seen whether the injury keeps him out of Euro 2020. He may be able to play a full part by wearing a protective fast mask.
Rudiger wrote on Twitter: "I'm really sorry for @DeBruyneKev's injury. Of course this was not intentional from me – I've already been in touch with Kevin personally and I really wish him a speedy recovery & hope we can see him back on the pitch very soon again."
I'm really sorry for @DeBruyneKev's injury. Of course this was not intentional from me - I've already been in touch with Kevin personally and I really wish him a speedy recovery & hope we can see him back on the pitch very soon again ✊🏾⚽ #UCLFinal— Antonio Rüdiger (@ToniRuediger) May 30, 2021
De Bruyne had earlier confirmed his injuries as an "acute nose bone fracture and left orbital fracture".
Belgium boss Roberto Martinez told CBS Sports that Rudiger should have been sent off.
"For me, Rudiger is very, very fortunate," Martinez said on Saturday night. "When you look at the replay there is no clash of heads. He's properly leaving the shoulder against Kevin.
"For me, it was excessive force and reckless. And it should have been a red card. It makes me feel devastated for [De Bruyne]."
Belgium, ranked by FIFA as the world's number one team, are due to begin their Euro 2020 campaign against Russia in St Petersburg on June 12, with further group games to follow against Denmark and Finland.