Stilian Petrov claims the performance of every Celtic player would drop 10 per cent if Roy Keane was to hang up his boots.

The former Manchester United and Republic of Ireland skipper has indicated this could be his last season at the top as he continues to be troubled by hip problems.

But Petrov is praying the 34-year-old continues playing because of his influence on those around him.

"He adds something to everybody’s game," said the Bulgarian international captain. "He gets 10 per cent more from everybody.

"On the pitch he fights and he shows what kind of player he is in training and in the games.

"He always wants to do his best. He always pushes you and he gives us more concentration."

Defender Stephen McManus agrees Keane would be "sorely missed" should he stop playing.

The young Scot said: "Roy is a top player and for as long as Roy decides to play on that’s great news.

"It’s a great pleasure to play alongside somebody who has played at the top like him.

"He will be sorely missed whenever he goes. When you lose top-class players it’s always a shame.

"He demands so much off everybody which is great and that improves your game.

"When someone like Roy Keane is having a wee word in your ear, and thinks you can add, then you’ve got to listen."

Keane does not look like a man in pain to Petrov, who actually believes he is getting sharper with every week.

"He doesn’t look like he’s got a problem at the moment," added the 26-year-old. "He’s been having problems and has told us a few times.

"But every game he looks sharper and we know how important he is for our team with his experience and his name.

"Every time he is on the team sheet other teams wince."