Ronald Koeman admitted his Saints side were made to pay for their mistakes as Manchester City won 3-0 at St Mary’s.
Saints had matched the Premier League champions during the opening 45 minutes, but errors in the second half allowed Yaya Toure and then Frank Lampard to score, before Gael Clichy added a third.
Speaking to youtube.com/southamptonfc after the game, Koeman felt the rare mistakes made by his players were the difference between the two sides.
He was also disappointed not to see his team take advantage of Eliaquim Mangala’s red card with the score at 1-0 for a foul on substitute Shane Long.
He said: “We didn’t play well. We know that when we play against a team like City who is very strong you have to be good to play and finally to have a good result.
“In the beginning the start was very nervous but after 20 minutes it was a little bit better and we had a little bit more control in the game. We had the first chance.
“City had one in the first half, but if you look at the first two goals, they are mistakes from us and they will punish you for that. It is difficult because you have to be better. You can’t do these mistakes because you will pay for that.
“I have to look back at that part of the game [after the sending off]. Maybe we lost organisation in the team, with changes and changes in positions to try and make a draw. You know with one less they still have the qualities to win and they showed that.”
With Arsenal up next on Wednesday for his side, Koeman says it is a positive that Saints will be back in on Monday to turn all their attention to the game at the Emirates.
He added: “The message after was we have to learn, we realise now we can’t make those mistakes and that’s the message. It is only three points. Wednesday is a new opportunity to win.
“We’re disappointed today but from tomorrow we prepare for Arsenal. Playing games is the best. We will recover from today and be prepared for the next one.”
Koeman revealed Morgan Schneiderlin made way at half-time due to injury, while he hopes to have Jack Cork available for Wednesday after he missed out through illness.
“He [Morgan] had an injury in his upper right leg, we have to wait, maybe we will know tomorrow [Monday] about if he will be okay for Wednesday. Jack I hope will be back, we need the players."