Jose Mourinho says Manchester United are relying on Romelu Lukaku to keep shouldering the goal-scoring burden until Zlatan Ibrahimovic returns to fitness.
The Belgian striker has been in red-hot form for United, scoring 10 times in nine appearances, while playing 90 minutes in each of those matches.
The 24-year-old's only rest came during United's 4-1 Carabao Cup victory over Burton Albion, and Mourinho says he will continue to lean heavily on Lukaku until Ibrahimovic works his way back from a serious knee injury.
"Without Zlatan, we cannot rotate the striker, especially because Marcus Rashford is playing also in other positions," said Mourinho, whose side face Crystal Palace on Saturday.
"So until the moment we have Zlatan, we cannot think about giving rest to our number nine the same way we give in other positions."
Lukaku faced a huge weight of expectation after completing his £90m move from Everton to United but, despite increased scrutiny on his performances, he has fitted in seamlessly at Old Trafford.
Mourinho refused to take credit for Lukaku's blistering start, instead insisting it is the result of hard work and steady, gradual improvement since he arrived in the Premier League as an 18-year-old in 2011.
"Every step in his career, he grabbed it with both hands, since his first loan to West Bromwich Albion," Mourinho added. "He grabbed that opportunity with both hands, fighting for his evolution.
"He was very strong in his desire to be playing in a team with other objectives now and with Champions League football. It was always his dream to come to this level.
"He works hard, he rests, he has a great professional life outside the football pitch and he has great ambition.
"So it is a global evolution. It wouldn't be fair if I didn't say that every step in his career with different managers, different players and different teams is not contributing to what he is now.
"Of course now, Manchester United is a different level of expectation and he is coping well."