A tunnel bust-up erupted after Manchester United's 3-1 win at Middlesbrough this morning, that lifted Jose Mourinho's team out of sixth place in the Premier League for the first time in 19 weeks.
There was a heated on-field fracas involving Middlesbrough's Rudy Gestede and United's Eric Bailly in stoppage time and the dispute continued after the game, coming to a head in the tunnel.
Bailly and his teammate, Ashley Young, appeared most unhappy.
Fielding a weakened team and playing its third game in six days, United looked like easing to victory after goals by Marouane Fellaini and Jesse Lingard a spectacular strike from the edge of the area put the visitors 2-0 up by the 62nd minute.
Middlesbrough, which fired manager Aitor Karanka on Friday, dominated the final half-hour and reduced the deficit in the 77th when Gestede took advantage of defensive errors to score from close range.
United held out despite late pressure and added a third in the third minute of injury time when Middlesbrough goalkeeper Victor Valdes, a former United player, slipped as he was about to make a clearance, allowing Antonio Valencia to walk the ball into the net.
United moved above Arsenal into fifth place with an eighth win in its last 11 matches in all competitions.
"The game was tough," Fellaini said. "They pushed and played long balls and are physical. We did it. We did well."
United manager Jose Mourinho was without suspended Zlatan Ibrahimovic and Ander Herrera, while Paul Pogba was injured and Henrikh Mkhitaryan was only on the substitutes' bench.