CELTIC boss Ronny Deila refuses to rule out Jason Denayer from Thursday's Europa League game against Salzburg.

But, if scans show that the Belgian defender - who limped off at half-time in the 2-1 win over Dundee at Parkhead - has sustained serious bone or ligament damage to his left ankle, the Hoops boss has no fears about pitching Efe Ambrose in for this vital game.

The Nigerian lost his central defensive position when Denayer joined the club on loan from Manchester City in August. Ambrose initially switched to right-back, but dropped to the bench when Mikael Lustig and Adam Matthews recovered from early-season injuries.

His last start was in the home defeat to Hamilton on October 5, and, before coming on for the second half against Dundee, he spent seven games limited to watching from the bench. If Denayer does not recover in time - Lustig is already ruled out for at least three weeks with a hamstring injury - Charlie Mulgrew is another option as a partner for Virgil van Dijk in central defence.

But the Scotland international has been a key player in midfield in recent weeks, and Ambrose has much more experience alongside Van Dijk after playing all last season there.

However, lack of game time in the past couple of months could count against Ambrose.

He looked rusty when he came on at the weekend, though Deila is confident his recent appearances at right-back for Nigeria in African Cup of Nations qualifiers will have offset this lack of match practice.

The manager said: "Efe has just played two games for his national team, and that was perfect for him. He has not played so much in central defence, but he is a clever player and he knows the position. Efe has also played many games there in European competition."

Whatever Ambrose may have lost in match sharpness, he has certainly retained in terms of confidence.

Despite having just spent the longest period of his time at Celtic out of the starting XI, he believes he is more than ready to step into the breach.

And, after a less-than-impressive display against Congo last week, he has caused a stir in his homeland after suggesting that playing against Lionel Messi, which he has done for Celtic and his country, was something he found easy.

Ambrose told SL10.ng: "You cannot call Messi a No.9 because he roves, so it's easy playing against him.

"The easiest player to play against is the one that doesn't come to bully you, and it's Messi, of course.

"He makes his move from afar. And, for me, if you play against someone like Messi, you'll have time to see what he wants to do.

"You have time to read his plan because he doesn't come to the centre-half, he plays from far away with his ability and dribbling skills.

"That's why I would say Messi is easier because Barcelona just pass and pass the ball. As a centre-half, you just have to keep to your zone. So, for me, I think Messi is easy."