Manchester United manager Louis van Gaal will not take any unnecessary risks with Anthony Martial for Tuesday's crunch Premier League clash at West Ham.
Manchester City's faltering form means United will leapfrog their bitter rivals and head into the final weekend of the season in the fourth and final Champions League spot if they are victorious at Upton Park.
West Ham boss Slaven Bilic has demanded a response from his players ahead of their final outing at the famous old ground, with Saturday's 4-1 humbling at the hands of Swansea City leaving a bitter taste.
United beat relegation-threatened Norwich City 1-0 at the weekend but lost Martial to a hamstring injury in the warm-up.
The 20-year-old France forward has impressed with 15 goals in his debut season at Old Trafford, but Van Gaal will not take the chance of him further aggravating the injury despite the high stakes.
"If his muscles are still tight I don't take any risks because he is a very important player," Van Gaal said.
"We don't want a rupture and that is very important for us."
United face Crystal Palace in the FA Cup final on May 21 after this weekend's closing Premier League match against AFC Bournemouth.
Van Gaal has dealt with persistent injury problems over the course of the campaign and, having opted to rest Marcus Rashford and Daley Blind for the trip to Carrow Road, he will continue to proceed cautiously for these final, pivotal encounters.
"It is always dependable on the data from my fatigue specialist," the Dutchman added.
"We are going home and Sunday is recovery and Monday is recovery. I have to decide then on the data of my fatigue specialist who I am taking with me.
"It's always like that. It can happen that I leave players at home because they are too tired.
"Last week we played against Leicester and it was cold, six degrees or something. Against Norwich it is 25 degrees.
"It's a big difference and you have seen that, you have seen that on the faces of the players."