Jose Mourinho confirmed Paul Pogba is a doubt for the Manchester derby in the Premier League on Thursday after suffering an injury in the 2-0 win at Burnley.
Anthony Martial and Wayne Rooney goals saw United move to within a point of fourth-placed Manchester City ahead of the potentially critical derby, but Pogba limped off in the closing minutes.
United are already without Zlatan Ibrahimovic and Marcos Rojo after the pair suffered "significant" knee ligament damage in the Europa League quarter-final against Anderlecht and Mourinho is unsure whether Pogba will recover in time to face City.
"I don't know," Mourinho said when asked about the world-record signing's fitness. "Dead he is for sure, if he's injured or if it's just the super accumulation of fatigue in the muscles, I don't know.
"But as I was saying, if he cannot play Thursday he cannot play Thursday, we play another one and we don't cry, like we didn't today."
United warmed up at Turf Moor wearing training tops bearing the names of Ibrahimovic and Rojo and Mourinho paid tribute to the duo, who are both set to undergo surgery.
"We cry because we have two important injuries to two amazing guys," Mourinho said.
"But we don't cry because we lose qualities on the pitch, we just cry because they are important injuries, with two important surgeries and two important periods of recovery. And we feel for our friends."