Ole Gunnar Solskjaer has been warned by former Manchester United striker Dimitar Berbatov that Cristiano Ronaldo may have left his team-mates "unhappy".
Ronaldo has announced his return to Old Trafford with a bang, scoring three goals in his opening two games for United.
The Portuguese backed up his double against Newcastle by opening the scoring against Young Boys, before being taken off in the 2-1 defeat in the Champions League.
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His fine early form is clearly a huge benefit to Solskjaer, and has prompted talk of a real challenge for silverware this season.
But bringing in a player of Ronaldo's quality is a double-edged sword, according to Berbatov.
The former Bulgaria international admits that with Ronaldo edging out the competition to start up front, the likes of Edinson Cavani and Anthony Martial will no doubt have been left upset.
Speaking exclusively to Betfair, Berbatov said: "Two games, three goals for Cristiano Ronaldo back in a red shirt. I'm not surprised by the immediate impact he has made at United and he will only get better as the season goes on.
"You cannot argue with his goalscoring and the aura that he brings to the team. The fans gave him a great welcome back last Saturday and he repaid them with two well-taken goals.
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"It will be interesting to see how Ole keeps the other players happy. He will have to decide how he uses the likes of Edinson Cavani and Anthony Martial. This is when managing a talented squad becomes difficult because players will feel hard done by.
"Cavani is probably unhappy. He had a great first season at United and how he's dropped down the pecking order and lost his number seven shirt.
"I hope Ole has had an honest conversation with Cavani about his plans for the team. As a player in this situation, you understand that the manager's job is to pick the best team, but you always want to play and become unhappy when you're left out."
Addressing the defeat to Young Boys, Berbatov admitted that United needed to step up their concentration after going down to 10 men, with Jesse Lingard's error proving costly.
"Aaron Wan-Bissaka's red card was a big blow to Manchester United against Young Boys but the Red Devils should have dealt with the situation better," he added.
"When you go down to 10 men, you need to be more focussed and more intelligent. United were neither and, in the end, a lapse in concentration from Jesse Lingard cost them.
"The result showed that United need to be more streetwise in the Champions League.
"Their players should not be getting red cards in the first half of away matches. But the occasion can get to players, cloud their judgement and lead to rash decisions. In the circumstances, a draw would have been a decent result."
