|Carragher and Neville demonstrate the enmity between the sides [GALLO/GETTY]
Manchester United beat Liverpool 2-1 with goals from Wayne Rooney and Park Ji-Sung to again go top of the English Premier League ahead of Arsenal and Chelsea, who drew 1-1 at Blackburn to put United in the driving seat at the end of the season.
Fernando Torres opened the scoring for the visitors at Old Trafford as he lost his marker and headed home from close range after five minutes.
But Antonio Valencia was hauled down by Javier Mascherano five minutes for a Manchester United penalty that should probably have been a free kick, with the foul beginning outside the box.
But referee Howard Webb pointed to the spot and Rooney prodded in the rebound after Pepe Reina had saved his initial effort.
Park headed the winner on the hour as Torres wasted a late chance to equalise.
United's victory ends arch-rivals Liverpool's run of three straight wins in this fixture and maintains the champions' quest to win a 19th English league title – one more than Liverpool.
Alex Ferguson's side are now two points ahead of second-placed Arsenal with seven games to play.
Chelsea blinked first in the race for the letting slip two points in a 1-1 draw at Ewood Park.
The result strengthened United's challenge to become the first English club to win four successive titles.
Chelsea failed to capitalise on their superiority at Blackburn to complete a miserable few days for Carlo Ancelotti's side after they were knocked out of the European Champions League by Inter Milan on Tuesday.
The Londoners grabbed the early initiative when Didier Drogba put them ahead after six minutes with his 22nd league goal of the season, but Rovers pulled level 20 minutes from time.
Chelsea failed to deal with a Michel Salgado cross which El-Hadji Diouf headed home at the far post.
"It's a difficult moment but we don't have to lose our confidence," Ancelotti told Sky Sports.
"It's been a hard week but every week is a hard week. Now we have to work hard and prepare for Wednesday's match at Portsmouth."
Art Old Trafford, the opening 10 minutes at Old Trafford were among the most incident-packed, and contentious, of the Premier League season as the ill feeling between the two old enemies became abundantly apparent.
First blood was drawn by Liverpool with a superbly-worked goal that suggested their hopes of another win over the defending champions might not be that far-fetched.
Steven Gerrard drove deep into United territory from just inside his own half before feeding the ball to Dirk Kuyt whose run continued to the right-hand by-line before he pulled back a pinpoint cross which found the head of Torres for a routine finish.
Old Trafford was stunned but it took just seven minutes for the home side to respond, the equaliser coming after Emiliano Insua made a weak defensive header which saw the ball fall for Valencia.
He immediately set off towards the Liverpool goal, with Mascherano snapping at his heels and bringing him down just as he entered the area.
With United insisting Mascherano's yellow card should have been red, Gary Neville sprinted half the length of the field to voice his opinion and engaged in an angry exchange with Jamie Carragher, one duplicated on the touchline by rival managers Ferguson and Rafael Benitez who engaged in a finger-pointing spat before the United boss roared his disapproval at Webb.
After the rows, Rooney's poor penalty was well saved by Jose Reina but the rebound falling kindly for the England forward, who was alert enough to turn the loose ball into the open net for the equaliser.
Korean Park's clinical diving header from six yards put the home side in front and they never looked like losing it aside from Torres scuffed chance late on.
Liverpool are four points behind Tottenham Hotspur in the race for the fourth European Champions League place, having played a game more.
They were overtaken in fifth by Manchester City when they won 2-1 at Fulham in the other late match.
Roque Santa Cruz and Carlos Tevez gave the Blues a 2-0 half-time lead before Danny Murphy scored a penalty with 15 minutes left.