The Duke had an operation on his troublesome shoulder yesterday while Roberts suffered a fractured fibula in Sunday's victory over Reading.
Roberts was on crutches when he picked up the Supporters' Club Player of the Year award at the JJB Stadium last night.
He has to rest the injury for six weeks but hopes to be ready to start his rehabilitation towards the end of June when the squad report back for pre-season training.
Partner-in-goals Ellington will have to wait and see what the consultant found during yesterday's surgery before learning the length of his recovery period.
But it could be three months if major repair work was needed, leaving him extremely doubtful for the start of the big kick-off.
Both players are likely to miss the players' holiday in Barbados paid for by Dave Whelan as a reward for reaching the Premiership – the squad and coaching staff jet out on Friday for a week.
And it will mean another striker is high on the club's summer shopping list to make sure Latics aren't left shy up front for the big kick-off.
Manager Paul Jewell told the Evening Post: "We are hoping it's nothing major with the Duke but that all depends on what the consultant found when he opened him up.
"The worst case scenario is up to three months but we're keeping our fingers crossed it won't be that long.
"It's an injury that has affected him – he's had to wear a big harness and strapping during matches.
"People kept asking me about him and why had he gone off the boil but he has been genuinely handicapped by it for virtually the whole of the season.
"It has popped out a couple of times so Duke deserves great credit for continuing through it all.
"This is the second time we've won promotion and he's had to go off for an operation on the shoulder.
"I had a long chat with Duke after the Preston game because he was running on nothing that day.
"But I told him I was convinced we'd beat Reading and that he would score.
"I think he had got a bit mixed up with what we expected of him and the tension of the situation had got to him.
"He's a lovely kid with a lovely smile and after the chat the shackles seemed to come off him in training."
Ellington got a 'get well soon' present from Latics supporters last night, finishing runner-up to Roberts in the player of the year poll, with Jimmy Bullard in third.
Lee McCulloch was voted Players' Player of the Year, with the prizes presented in front of 10,000 fans at the promotion party.
After collecting his award, Roberts revealed he had played for more than 50
minutes of the Reading game with the fractured leg, scoring in the process.
The striker said: "I did it in the 10th minute but didn't think it was too serious and stayed on until the 63rd minute.
"I've fractured the fibula and it's six weeks on crutches without putting any weight on it. Hopefully I'll be back in time to start training with the rest of the boys when they come in after the summer holidays.
"The injury is just one of those things and it's better to have done it in the last game rather than during the season."
Meanwhile, Jewell has confirmed he is taking the squad to Denmark as part of their pre-season training programme.
He said: "We report back during the last week in June and we go to Denmark on July 17 for a few days.
"I'm in the process of finalising our friendly matches which with all respect might not be the most attractive.
"But I'm a great believer in pre-season not being too high profile."
Roberts was on crutches when he picked up the Supporters' Club Player of the Year award at the JJB Stadium last night.
He has to rest the injury for six weeks but hopes to be ready to start his rehabilitation towards the end of June when the squad report back for pre-season training.
Partner-in-goals Ellington will have to wait and see what the consultant found during yesterday's surgery before learning the length of his recovery period.
But it could be three months if major repair work was needed, leaving him extremely doubtful for the start of the big kick-off.
Both players are likely to miss the players' holiday in Barbados paid for by Dave Whelan as a reward for reaching the Premiership – the squad and coaching staff jet out on Friday for a week.
And it will mean another striker is high on the club's summer shopping list to make sure Latics aren't left shy up front for the big kick-off.
Manager Paul Jewell told the Evening Post: "We are hoping it's nothing major with the Duke but that all depends on what the consultant found when he opened him up.
"The worst case scenario is up to three months but we're keeping our fingers crossed it won't be that long.
"It's an injury that has affected him – he's had to wear a big harness and strapping during matches.
"People kept asking me about him and why had he gone off the boil but he has been genuinely handicapped by it for virtually the whole of the season.
"It has popped out a couple of times so Duke deserves great credit for continuing through it all.
"This is the second time we've won promotion and he's had to go off for an operation on the shoulder.
"I had a long chat with Duke after the Preston game because he was running on nothing that day.
"But I told him I was convinced we'd beat Reading and that he would score.
"I think he had got a bit mixed up with what we expected of him and the tension of the situation had got to him.
"He's a lovely kid with a lovely smile and after the chat the shackles seemed to come off him in training."
Ellington got a 'get well soon' present from Latics supporters last night, finishing runner-up to Roberts in the player of the year poll, with Jimmy Bullard in third.
Lee McCulloch was voted Players' Player of the Year, with the prizes presented in front of 10,000 fans at the promotion party.
After collecting his award, Roberts revealed he had played for more than 50
minutes of the Reading game with the fractured leg, scoring in the process.
The striker said: "I did it in the 10th minute but didn't think it was too serious and stayed on until the 63rd minute.
"I've fractured the fibula and it's six weeks on crutches without putting any weight on it. Hopefully I'll be back in time to start training with the rest of the boys when they come in after the summer holidays.
"The injury is just one of those things and it's better to have done it in the last game rather than during the season."
Meanwhile, Jewell has confirmed he is taking the squad to Denmark as part of their pre-season training programme.
He said: "We report back during the last week in June and we go to Denmark on July 17 for a few days.
"I'm in the process of finalising our friendly matches which with all respect might not be the most attractive.
"But I'm a great believer in pre-season not being too high profile."