Pep Guardiola admitted Kyle Walker deserved to be sent off as Manchester City's winning run came to a shambolic end.
City were already through to the last 16 as group winners, but conspired to mess up the dead rubber, with the end of their seven-match winning run, Walker's dismissal and two injury concerns.
England defender Walker was shown a straight red in the 82nd minute for lashing out at Andre Silva and could see his automatic one-match suspension extended by UEFA.
Walker will certainly miss the first leg of City's last 16 tie next February, but could miss a further two games, if UEFA's disciplinary body decides he deserves further punishment.
Guardiola was tight-lipped after City's defeat, but offered no defence for Walker's actions. “It was a red card, definitely,” he said.
“But I’m not coming here to say what happened in the dressing-room.
“We played better in the second-half, were more aggressive, but we lost, so congratulations to Leipzig.
“In the first-half, we lacked the rhythm. The second-half was much better, but unfortunately we made one or two mistakes and they punished us."
Defending his decision to start Walker, rather than give one of City's youngsters a rare chance, Guardiola said: “Kyle didn’t play at Aston Villa, so he didn’t have many minutes in the last weeks, so it was good for his rhythm to play.”
City defender Oleksandr Zinchenko said: "Unfortunately Kyle got the red card. He was disappointed in the dressing-room. But there's no time to be sad, we have to react well, we have to move on. "
As well as defeat and Walker's sending-off, City have injury concerns over Phil Foden and Nathan Ake, both of whom were forced off.
“Nathan has a problem with his back, we'll see how he is tomorrow,” said Guardiola.
“Phil had problems at the beginning of the game with his ankle. He struggled a little bit, so he was taken off as a precaution.”
