document: The 28-year-old Italian, who joined the Black Cats from Arsenal in 2013, was injured during a training session.
  Manager David Moyes said he would "definitely" look to make a signing as Jordan Pickford, 22, is his only fit senior goalkeeper.
  Moyes added the club had made a bid for Sevilla midfielder Vicente Iborra.
  The 28-year-old joined Sevilla from Levante in 2013 and is a three-time Europa League winner.
  Moyes said Mannone's injury gives Pickford "the chance to show what he can do".
  He added: "He has a big future ahead of him."
  The England Under-21 international is a product of the Sunderland academy and has played for a host of clubs on loan.
  He made his senior debut for the Black Cats in an FA Cup tie at Arsenal last season, before making two Premier League appearances.
summary: Sunderland goalkeeper Vito Mannone will be out for at least three months and could require an operation after tearing elbow ligaments.