Manchester United manager Jose Mourinho questioned the fight of some of his players, despite the club's victory at Swansea City.
United eased past Swansea 3-1 on Sunday to end a four-match winless streak in the Premier League.
Mourinho was forced to use a make-shift defence for the trip to Liberty Stadium, with duo Chris Smalling and Luke Shaw late withdrawals, while Daley Blind was only fit enough for the bench.
Ashley Young, Phil Jones, Marcos Rojo and Matteo Darmian completed the back four, and Mourinho had some words for players who deemed themselves unfit on the weekend.
"I have a friend who is a big tennis player and he tells me when he remembered more the times he plays with pain than the times he plays without pain," Mourinho said.
"To compete you have to go to the limit. It is cultural for some - and that is not my culture. More than me, it is Man United.
"We have players with problems. At every sport - and I know because I have friends in others sports and they play at the highest level in their sport, and how many times they play when you are not 100 per cent."
United are sixth in the Premier League after 11 matches, eighth points adrift of leaders Liverpool heading into the international break.