Dyer, who is suspended for the Villa game, was in inspired form as the Magpies beat Coventry 3-1.

But Robson is sweating over whether Dyer warrants surgery over his shin splint injury.

"He's having a bone scan today and we're going to use the two weeks that we know we can't use him professionally," said Robson.

"We're going to give him the best attention, we're going to get to the root of the problem. He's having the bone scan to make sure that there is nothing in the shin itself and the muscles off it which is causing the problem.

"We'll have a look at all that because we need to know for sure that, after his two weeks of suspension, we have got him back on track ready to play again.

"While Alan is progressing very well, we can forget about him for at least a month, and Cort maybe about the same, so Kieron is absolutely essential for us to keep picking up sufficient league points to first of all make us completely safe for next season, and then keep us challenging for whatever we think we can challenge for."

Dyer's ban, and that of Peruvian midfielder Nolberto Solano, who was dismissed during the same game, have left Robson once again reshuffling his pack, but he has at least been boosted by the return of Scottish international Gallacher for the clash with John Gregory's side.

The former Blackburn Rovers player has been out for 10 weeks with a combination of hamstring and calf injuries, and after starring and scoring for the reserves last week, he could be asked to partner teenager Shola Ameobi in attack despite his lack of match practice.

Midfielder Rob Lee will not be risked at Villa Park as he battles against his own hamstring problem, and Newcastle will also have to do without on-loan defender Wayne Quinn, who performed well in his debut against Coventry but was not registered in time to qualify for the cup tie, Andy Griffin returning in his place.

Despite his lack of resources, Robson has no intention of giving up on a competition in which his team has not lost away from Wembley in the last three seasons.

The sides drew 1-1 at St James' Park on January 7 as Solano's late equaliser handed United their replay after Steve Stone had put the visitors in front, and with a home draw against Leicester awaiting the eventual winners, the stakes remain as high as ever.

"We know that in the next round, there is a possibility of a home win whichever team wins," said Robson.

"Leicester won't be easy, but they're now just hitting a patch and it's not very far away.

"You know anybody who gets through the fourth round, there will be many, many Premiership clubs going out because of the fact that there are some all-Premiership ties.

"Anybody surviving the fourth round will find themselves excited and in with a chance, so we're trying to play for the fourth round.

"We know it has to be decided on the night, so we're prepared for that and we'll give it the biggest attention we can give it."