Chelsea manager Antonio Conte has defended Jose Mourinho's decision to sell Kevin De Bruyne and Romelu Lukaku during the Portuguese's time at Stamford Bridge.
Mourinho this week criticised United's decision to move on Angel Di Maria, Javier Hernandez and Danny Welbeck during Louis van Gaal's reign as manager.
Conte was asked on Friday whether Mourinho was mistaken in his judgement in offloading De Bruyne and Lukaku, both of whom have gone on to have significant success with Manchester City and Everton respectively.
Mourinho and Conte have been at odds throughout this season, with the pair embroiled in a touchline spat during Chelsea's FA Cup defeat of United on Monday.
But the Italian was diplomatic when quizzed on his assessment of Mourinho's transfer policy at the Blues.
"It's always very difficult to take always the best decision," he said. "Sometimes it can happen that you think one thing and then, in the future, something else happens. A different situation.
"I think, above all, in football it's not simple to give always a correct evaluation for players.
"Sometimes a player who, in the last two years or so, didn't play well goes on to have a fantastic season. That happens. But it's not right to talk about mistakes."