A scuffle during the half-time interval was instigated by an unexpected attack on Manchester United goalkeeper David De Gea by one of the Liverpool players.

Police had to intervene to prevent emotions from getting out of hand during the heated encounter. The United keeper was spat on as he walked to the Old Trafford dressing room, according to sources contacted by the Sun.

The game had already gotten off to a bad start with Luis Suarez refusing to shake the hand of Patrice Evra before kick-off. 

De Gea hardly had any reason to worry during the opening half with the Liverpool attack failing to muster a decent shot on target. And in the second half, his job was made even easier as Wayne Rooney fired two quickfire goals but the Spaniard failed to keep a clean sheet as Suarez capitalised on a mistake by Rio Ferdinand when he had to deal with a Charlie Adam delivery in the 80th minute. 

But off the field, the goalkeeper did not have the best of times due to the spitting incident. 

Although it is is unclear who was responsible for the spitting, one source told The Sun: "De Gea was making his way to the tunnel and was clearly shocked to be spat at.

"Obviously the players reacted angrily and both teams became involved, before stewards managed to quieten it down."

Tempers were frayed again at the end of United's 2-1 victory when Liverpool substitute Craig Bellamy got involved in a confrontation with the Old Trafford head of security as players left the pitch. 

Moments earlier, Patrice Evra was seen celebrating the victory in front of Suarez as the latter was trudging off the pitch angering several Liverpool players.