Sunderland head coach Dick Advocaat has warned that the team could be relegated from the Premier League unless they improve their performance levels.

The Black Cats conceded four goals in the space of 14 second-half minutes as they fell to a 4-1 home defeat at the hands of Crystal Palace on Saturday, which came less than a week after they beat rivals Newcastle United at the Stadium of Light.

Advocaat says that there is cause for concern ahead of Sunderland's final six games of the season.

"I am worried, yes, very worried," the Dutchman told the Northern Echo. "I think I am as worried as the other coaches who are in the same position as ourselves, but if you can do it against Newcastle, we should repeat it.

"We are not the first team to get beaten by Palace because they have beaten better teams in the last nine games, but we have to believe in ourselves.

"We showed we can do something against Newcastle, but if we carry on performing like this then we have no chance. We still have to believe that we can do something, and I actually believe we can."

Sunderland are three points clear of the drop zone.