Aston Villa manager Paul Lambert has admitted that he was shocked by Sunderland's decision to sack Martin O'Neill at the weekend.

The Black Cats are just one point above the relegation zone in the Premier League, having failed to register a win since January 16, following their 1-0 defeat to league leaders Manchester United on Saturday.

Sunderland have since named Paolo Di Canio as their new boss, but Lambert believes that the sacking of O'Neill highlights the insecurity of a Premier League manager's job.

"I was shocked like everybody else at what had happened," Lambert told Sky Sports News. "I was shocked.

"Nobody is safe. I had the privilege of working under him for five years and it was fantastic.

"If you make that change, you'd think someone is going to be appointed pretty quickly there at this stage of the season."

Sunderland travel to Stamford Bridge to face Chelsea in their next match.