The 29-year-old, a summer capture from Fulham, has a stunning record for Northern Ireland having found the back of the net 34 times in just 64 senior appearances.

However, he scored only four times in 30 games, 15 of them as a substitute, for the Londoners in a frustrating year at Craven Cottage.

But Keane is convinced that the Downpatrick-born player will prosper at the Stadium of Light.

He said: "Sometimes that happens with players - and sometimes players have a great record at club level and they can't quite seem to do it at international level.

"Hopefully David will plug into what we are all about. He has settled in very well.

"I am pretty sure when David gets a chance, he will score goals for Sunderland."

Healy did just that when he marked his debut with an extra-time winner in the 2-1 Carling Cup second round win at Nottingham Forest, and he will hope for a first start at Wigan on September 13.

He is currently on duty with his country in Slovakia as the World Cup qualifying campaign gets under way, and with 14 of his club-mates also on international duty, Keane's squad for training has been reduced markedly in size.

However, he insists those who have stayed behind will get plenty done.

Keane said: "You would be surprised. We still have a decent group staying behind, we have still got the reserves.

"We will possibly have a practice game at the end of the week for the likes of Anton [Ferdinand] and one or two other lads who are catching up on their fitness, so we will have enough to have some decent training sessions."