Manchester City will check defender Vincent Kompany after training today before deciding whether he can feature at Saints tomorrow.
Kompany has been sidelined by a calf injury that was expected to keep him out until after next week's FA Cup fifth-round tie with Leeds.
However, the Blues skipper returned to training on Wednesday and could be available at St Mary's.
"We are optimistic," said manager Roberto Mancini.
"He trained yesterday, and two days ago. After today we will decide."
Mancini also confirmed Yaya and Kolo Toure will be available after Ivory Coast's earlier than expected exit from the African Nations Cup.
"I am sorry because they didn't win but I am happy because they are here," said the Italian.
Mancini is refusing to accept his side are out of the Premier League title race, even though City have fallen nine points behind Manchester United.
However, he said City's hopes will be aided by United's continued progress in the Champions League, where they face Real Madrid on Wednesday.
"It is normal when you play against Real Madrid you can lose some strength," he said.
"I will be supporting United to go through."