Duff was injured after scoring against Crystal Palace in September

The 27-year-old Northern Ireland international is close to making a first team return after five months out with ligament and hamstring problems.

Caldwell told BBC Radio Lancashire: "The attitude of the guy from day one has been magnificent.

"He's knuckled down, he never looked negative and worked very hard."

Duff was due to undergo two lots of surgery but the second operation, on his cruciate ligament, was cancelled when it was discovered the ligament had started to heal itself.

He's a very good friend of mine and I'm very pleased he's back and in the running for a first team spot soon Burnley captain Steven Caldwell

Caldwell added: "Everyone was gutted for Michael when it happened, he is an important member of the squad but I think in a way he's had his just rewards with the news that it wasn't as bad as first feared".

Duff suffered multiple ligament damage during a game against Crystal Palace at Turf Moor on 29 September and was expected to be out for 12 months.

"He's looking good in training and I'm sure after a couple of reserve games he will be vying for a place in the side.

"He's a very good friend of mine and I'm very pleased he's back and in the running for a first team spot soon."