Forward Afu, a 21-year-old Tongan international, finally linked up with the Castle Park club this week after receiving international clearance to complete a protracted move from Australian Super 14 side Queensland Reds.

Although the signing was announced over a month ago, the lock or back row has only just received the green light giving the Knights a much needed boost following a disappointing 18-9 defeat to Nottingham last Sunday.

An impressive outing in the A team clash at Nottingham on Monday night has put Afu firmly into the thoughts of director of rugby Lynn Howells, who may decide to throw the youngster straight into the firing line after Kettle was ruled out with a broken finger.

Howells said: "Josh played 45 minutes in the A team, which was impressive as he had been travelling for four days, and he came through it well.

"He looked okay but obviously you can't say a lot from a 45 minute run-out in the A team.

"We will see how he gets on in training and, if he picks things up relatively quickly, hopefully he will come into contention."

The Welshman added: "Adam has broken his finger and has had a pin put in so he'll be out for six weeks.

"It is a big blow because he has been playing well for us and also led the side very well at the start of the season.

"But he's been playing with a groin injury so it will give him time to recover from that as well."

Kettle's injury completed a miserable day for the Knights as they slumped to their second defeat of the season.

After conceding three touchdowns in the opening 30 minutes they never recovered and failed to score a try for the first time this season.

The afternoon did not start well for Doncaster with Jamie Lennard replacing winger Justin Bishop, who suffered an early knee injury, and a couple of minutes later the home side got off the mark through Tim Taylor's try.

A drop goal from Ali Warnock reduced the deficit but Nottingham extended their lead four minutes later with fly half Taylor scoring a second try and David Jackson adding a third on 31 minutes to put them 15-3 ahead.

Lennard kicked two penalties but Jackson had the final word with a penalty just before the break.

Doncaster battled hard throughout the second half and defended well but could not earn a vital bonus point.

Howells said: "I think we deserved a losing bonus point but unfortunately we didn't get that.

"Changes will be made this weekend because it's unacceptable not to create chances - and that was the biggest disappointment for me."