Manchester United manager Ole Gunnar Solskjaer is awaiting the results of a scan to determine the severity of Paul Pogba's thigh injury after the star midfielder was substituted in the first half of a last-gasp 3-3 draw against Everton.
Pogba hobbled off the field with six minutes remaining prior to half-time as United capitulated at Old Trafford, where Everton sensationally salvaged a point in the 95th minute on Saturday.
United were in control when Pogba succumbed to injury – leading 2-0 at the interval thanks to Edinson Cavani and Bruno Fernandes – before two goals in the space of three minutes to start the second half restored parity for Everton.
Scott McTominay put United ahead again with 20 minutes remaining, but just as the Red Devils looked like securing maximum points, Dominic Calvert-Lewin silenced the hosts in the fifth minute of stoppage time.
Asked about Pogba post-match, Solskjaer told reporters: "It seemed like a muscle injury, his thigh.
"We will check him tomorrow, give him treatment and a scan, see how bad it is. We hope it's not too bad.
"He couldn't carry on, we had to take him off."
United's collapse dented their Premier League title hopes, with rivals and neighbours Manchester City – who have played two matches less – two points clear atop the table ahead of Sunday's showdown against champions Liverpool.
Saturday's result was just the fourth time in Premier League history United failed to win a fixture in which they led by two-plus goals at half-time, and just the second time at Old Trafford – 2-2 at Tottenham in December 1998, 2-2 at home to West Brom in October 2010 and 5-5 away to WBA in May 2013.
It was also just the fourth time United led a Premier League home game by at least two goals and failed to win, with Everton responsible for the last two occasions (also 4-4 in April 2012).
Fernandes scored a memorable long-range goal on the stroke of half-time to put United 2-0 ahead of Everton, following Cavani's opener.
Since his debut in the Premier League, only Liverpool's Mohamed Salah (22) has scored more Premier League goals than Fernandes (21). Meanwhile, only Southampton star James Ward-Prowse (five) has scored more outside the box than the Portuguese (four).