Manchester City manager Pep Guardiola: "We were not good in our build-up and we lost simple balls with our passes because we were not clever today, and a little bit sloppy.
"We have to compliment Southampton and move forward.
Arsenal boss Mikel Arteta told BBC Sport: “The first goal was the most disappointing, we were in control of the game, we took the game exactly where we wanted to.
"The first action they have, we fail to stop the cross and Gundogan has a free header in the middle of goal.
"Eleven against 11 against Brighton is tough, 11 against 10 is difficult so we have to improve for the final," said Guardiola.
"Unfortunately after 0-2, we conceded a goal so quick and after they push a lot, we were more tired and could not keep the ball as much as possible - we could not do it and unfortunately we lost the game.
Newcastle manager Steve Bruce, speaking to BBC Sport: "Overall our attacking play was good on the counter-attack and we just weren't quite good enough on the night.
"The biggest compliment I can pay them is that it's difficult to set up against them.
Man City boss Pep Guardiola to Sky Sports: “It was a tight game, but in general we played really good. We miss our chance in last minute of first half with the penalty.
"They are a top side and we were playing better.
Manchester City boss Pep Guardiola told BBC Match of the Day: "We did not create enough for the forwards. It is part of the game.
"In the last 10 minutes they had other chances, they are fast and can do it.
"We must look at the game because we made a couple of mistakes under the pressure of City and they are very dangerous and they will punish you," said Wolves boss Nuno.
"City are very talented; amazing players, amazing manager.
Manchester City manager Guardiola, speaking to BT Sport: "It was really difficult. They have the physicality, they have the quality of players.
"After 10 or 15 minutes today we realised we were not going to paint anything beautiful.
Liverpool manager Klopp told BBC Sport: "I saw a really good game and big mistakes. In each game, when you make these kind of mistakes, it's very likely you concede goals.
"It's easy to agree that the first half was a really good game, two sides really trying a lot to cause problems for each other, and I liked a lot I saw in the game.