Romelu Lukaku has been accused of looking unfit, with Gary Neville claiming that Manchester United face a “big decision” on the striker’s future this summer.
Lukaku played the full 90 minutes against his former club, with strike partner Marcus Rashford forced off with an untimely injury in the second half.
He put in a typically battling performance and caught the eye with his physicality and ability to hold up the ball, but did appear to tire easily amid questions of his training regime and ongoing presence at Old Trafford.
Former United defender Neville told Sky Sports of the burly 25-year-old: “Lukaku is the most interesting for me.
“You watch him for 25 minutes and he looks like a world beater. Then you see him make one big run and he looks absolutely shot.
“He was a brilliant performer, then you say to yourself he always looks tired after one or two big runs.
“He's a big decision. I've got very little sympathy for anyone who's unfit as a professional footballer.”
Neville believes it is up to Lukaku, not United’s backroom staff, to ensure that he is in the best possible condition.
He added: “Football players, they're like a clock ticking, they should know their bodies inside out.
“You get to that point as a football player, there's a routine. I'm not sure how he hasn't corrected it and found a system during the week which is his training, his nutrition.
“It's not a reflection against the sport science of the club, it's something that's not quite right.”
Lukaku is close to completing a second season with United following a £75 million ($97m) transfer in the summer of 2017.
He recorded 27 goals in his debut campaign, but has managed only 15 this term.
Ole Gunnar Solskjaer has not always found a starting berth for the Belgian, but has favoured him over recent weeks while seeking an attacking spark to fire the Red Devils into the top four.
Such a finish now appears to be beyond United, with a 1-1 draw at home to Chelsea keeping them stuck in sixth spot.