Mancini criticizes Hart for mistakes
Hart fumbled his save of Rickie Lambert's shot to allow Steven Davis to bundle home the rebound as City's Premier League title hopes were dealt a hefty blow.
He had also failed to clear in the build-up to Jason Puncheon's ninth-minute opener, allowing the Saints man to stab home.
The 25-year-old keeper has made several high-profile errors this season and Mancini has hit out at the shot-stopper.
He was quoted as saying in The Sun: "Joe has made too many mistakes. He has not been good enough. It was a really bad mistake from Joe. It was not good enough. It's not strange because he's done a few mistakes this year."