Paddy McNair has suffered an injury setback and looks set to miss out on Northern Ireland's crucial World Cup qualifiers against San Marino and the Czech Republic in September.
The Sunderland defender was expected to return for pre-season training after rupturing knee ligaments in November.
But the 22-year-old has not made the progress he had hoped and has now been told that he is likely to miss the opening six weeks of the season.
His name was missing from a 40-man squad who journeyed to League One Bury for their first pre-season fixture on Friday, though he will travel with them to Edinburgh for a match against Hibs today.
Boss Simon Grayson, who recently left Championship rivals Preston to take over the Black Cats hot seat, said: "Paddy has had a setback with his knee and needed a bit of a clean-up. It means he will probably miss the first six weeks of the season, which is a blow.
"Obviously he will be a bit behind schedule when he returns. Sometimes these things do happen after a long injury. He is in good hands and when he does come back he will be in the right condition.
"I've not had a chance to talk to him yet having been in Austria with the rest of the squad, but we will take him up to Scotland with us. (Winger) Duncan Watmore has a similar injury and they are two key players. We wish them a quick recovery."
Northern Ireland manager Michael O'Neill will be bitterly disappointed to be without McNair again in the autumn World Cup qualifiers. McNair has missed the last two qualifiers against Norway and Azerbaijan due to injury and O'Neill had hoped he would be back for the games against San Marino, Czech Republic, Germany and Norway in Oslo.
Former Manchester United Academy graduate McNair will be expected to stand up and be counted on his return to club action and Grayson has no doubt that he can pick himself up after a series of setbacks. He joined Sunderland last summer from the Old Trafford side despite Jose Mourinho urging him to stay at fight for a place.
After scoring an own-goal within five minutes of making his debut at Manchester City, he enjoyed a string of encouraging performances in a struggling team before injury curtailed his season.
Grayson added: "Paddy will definitely be a handful in the Championship, but we like to think all the players on our books will be a handful at this level. They all have reputations for being Premiership players and now they are Championship players and they have got to earn the right. The Championship can be harum-scarum and it is a learning curve, but hopefully they will learn very quickly."