Wayne Rooney scored twice as Manchester United beat Liverpool 2-1 on Saturday in an ill-tempered match to provisionally move top of the Premier League.
Players from both teams had to be separated in the tunnel at halftime after Liverpool forward Luis Suarez refused to shake United defender Patrice Evra's hand before kickoff. Suarez was making his first start since serving an eight-match ban for racially abusing Evra in October.
Police and stewards had to shepherd the players into their dressing rooms at halftime after an altercation ensued when Evra tried to confront Suarez.
When the second half started, Rooney scored twice in the opening four minutes to place United firmly in control.
Suarez scored a consolation goal in the 80th minute.
There were also ugly scenes after the final whistle as Evra celebrated wildly and appeared to be attempting to provoke Suarez, an act which again saw police, stewards and match officials involved in ushering players from the field.
A disappointing game burst into life immediately after the halftime interval.
Ryan Giggs' right-hand corner was helped on by Michael Carrick and the unmarked Rooney was able to volley in his 16th goal of the season from six yards.
It took less than three minutes for Rooney to double the lead after Jay Spearing lost the ball to Antonio Valencia in midfield after 49 minutes.
The United winger carried the ball into the Liverpool area before slipping through the perfect pass that Rooney finished emphatically from a dozen yards.
Suarez finally made a telling contribution to the outcome of the match 10 minutes from the end.
Carrick brought down Suarez and Charlie Adam's free kick into the six-yard box was miscontrolled by Rio Ferdinand, allowing Suarez the simple task of slotting home the loose ball from close range.
Glen Johnson came close to finding a dramatic equalizer when his 20-yard shot was tipped over acrobatically by David de Gea.
The football on display in the first half failed to live up to expectation with the best opportunity of the opening period falling to United after half an hour when Giggs' cross found Paul Scholes whose header was saved superbly by Pepe Reina.
After his brace, Rooney might have claimed a hat-trick goal but lost his balance and shot wide after Scholes dummied a Valencia pass.
Welbeck also failed to convert two opportunities to kill off the game - the first blocked by Johnson, the second a wild shot over the goal.