Sunderland are in danger of getting relegated to the Championship at the end of the season.
Sunderland are third from bottom in the league table at the moment and are in real danger of going down to the Championship at the end of the season.
The players will have to be on top of their game between now and the end of the 2015-16 campaign in order to retain their English top-flight status for next season.
Former Sunderland star Bennett believes that defenders Kone and Kirchhoff and striker Defoe will be hugely important for Sam Allardyce’s team.
“You just have to look at the spine of the team,” former defender Bennett told The Sunderland Echo when asked about the key men in Sunderland's fight for survival.
“From Kone, Kirchhoff, Defoe. Kirchhoff gets on the ball and makes things happen. He is getting fitter and is a key player. Kone is no-nonsense and has fitted in well.”
Sunderland will return to action this afternoon when they take on Leicester City at the Stadium of Light in the Premier League.
The Black Cats will head into the game against the league leaders on the back of a goalless draw with West Bromwich Albion at home.