Sergio Aguero has been ruled out of title-chasing Manchester City's Barclays Premier League clash with Saints tomorrow.

The Argentina striker, City's top scorer this season with 26, has returned to training after missing four games with a hamstring injury but is not yet match-fit.

Manager Manuel Pellegrini had previously expressed hope the 25-year-old might be ready for Saints' visit to the Etihad Stadium, but next week's trip to title rivals Liverpool is now the target.

Pellegrini said: "Sergio is okay. He has worked just now with the squad but he just started on Thursday, so he needs more work to be 100 per cent fit.

"He is not in the squad but he doesn't have any problems with his injury.

"For this week it is too soon for him to start playing because he just worked two days, but next week against Liverpool he will not have any problems."

City are also still without defender Matija Nastasic, who suffered a knee injury two months ago.

Pellegrini, speaking at a press conference to preview the Saints match, was unwilling to confirm reports new contract talks have begun with midfielder Samir Nasri.

The Chilean said: "We are just thinking about this match we have to play against Southampton.

"All the other things - you are always talking and thinking and working - but in this moment it is not the most important thing."

City head into the game third in the table, trailing leaders Liverpool by four points but with two games in hand.