Manchester United players were involved in a shouting match at half-time of Sunday's win over Liverpool, midfielder Morgan Schneiderlin has said.
Louis van Gaal's side struggled to gain a foothold during the first half at Anfield but ultimately snatched a winner 12 minutes from time through captain Wayne Rooney.
Liverpool defender Mamadou Sakho claimed to French television after the match that United players were rattled at the break and Schneiderlin admits there were some heated exchanges prior to an improved second-half display.
"In the first half, we didn't win enough second balls. Sometimes we won the first ball but not the second ball," he told MUTV.
"When we came into the dressing room after the first half, there was some screaming and shouting but of course that is normal because in a derby you cannot lose the battle.
"Liverpool are a very high-pressing team and we knew if we kept a clean sheet we would have a chance to win the game.
"In the second half we did what we had to do. We scored one goal, stayed strong and, at the end, it is three points which is amazing."
Rooney's fourth goal in three Premier League matches proved the difference and Schneiderlin hopes he continues his strong form in 2016 so far in order to keep United in the trophy hunt.
He added: "Wayne is still the main figure at the club, he's the one guy who has scored so many goals in his career and he will keep doing it. Sometimes you have spells where you don't score but he has kept the smile on his face and trained hard.
"You saw his two goals against Newcastle were very good and today he scored another amazing goal. We need him in the second half of the season if we are to achieve something special."