Javier Mascherano saw red and the frustrations of Liverpool's failed Premier League title challenge boiled over.
The dying embers of Liverpool's campaign were finally extinguished at Manchester United on Sunday when the Argentina midfielder received a second yellow card for dissent toward the referee. Already trailing 1-0 before being reduced to 10 men, the Reds conceded two further goals to the league leader.
Liverpool is 14 points adrift of its fiercest rival and now faces a battle to cling onto the fourth Champions League qualification berth, starting next Sunday against fifth-place Everton.
It maintained manager Rafa Benitez's dismal record against Man United's Alex Ferguson in the league, having lost seven games and drawn one.
The game's turning point came a minute before the break, when Fernando Torres' protests to referee Steve Bennett at Rio Ferdinand's foul resulted in a booking.
Perhaps having heard Benitez's earlier pleas for Torres to receive greater protection from referees, Mascherano was furious at his teammate's rebuke and charged toward Bennett _ despite having already been booked in the 10th for a late sliding tackle on Paul Scholes.
"Clearly, he didn't say anything," Benitez said. "Ryan Babel was close to him, he didn't say anything, he was asking what happened. In these big games, to lose a player in this situation ... it's strange because Javier Mascherano is a good professional and was really surprised with the sending-off."
Ferguson questioned Mascherano's conduct, echoing last week's plea for players to respect referees in the wake of Chelsea's Ashley Cole turning his back on referee Mike Riley while being booked at Tottenham on Wednesday.
"Mascherano has been booked and kept badgering the referee," Ferguson said. "I don't know why he was involved. He came across the field from central midfield to argue with the referee.
"With all the things that happened in midweek with Ashley Cole, there has been a focus on dissent."
While calm in his initial protests to Bennett, Mascherano erupted after being dismissed, continuing to harangue the referee as captain Steven Gerrard attempted to calm the situation.
After an open first half, Benitez blamed the sending-off for changing the course of the game.
"After the sending-off, the game was almost finished," Benitez said. "We pressed a little bit in second half, but they had quality and ability."
Liverpool goalkeeper Pepe Reina was at fault for United's opening goal in the 34th, having almost palmed the ball into his own net a minute earlier.
Rushing out to punch clear Wayne Rooney's curling cross, Reina was beaten to the ball by defender Wes Brown, who headed it over the line for his first goal in three years.
The Spanish goalkeeper again came for the ball and missed in the 79th to end any hopes of a comeback.
Having missed with the goal at his mercy, Ronaldo headed in his 34th goal of the season from the resulting corner as Reina mistimed his attempted punched clearance.
Liverpool's misery was completed a minute later when Nani cut inside two defenders to hit home.
But it was another frustrating afternoon for Wayne Rooney, who hasn't hit the target at Old Trafford since October.
The first opportunity to end his goal drought came in the sixth minute when the England striker outpaced Jamie Carragher, but shot straight at Reina from point-blank range. His final touch was lacking again three minutes later when picked out by Paul Scholes from a free kick.
With United ahead through Brown, Rooney's tame header in the 40th from Ronaldo's free kick was easily collected. His profligacy persisted after the break. One-on-one with Reina in the 56th, he cracked the ball at Reina's feet.
Ferguson is still preparing for a tense conclusion to his team's title defense with seven rounds left.
"It was a really good performance _ a performance of maturity," Ferguson said. "We've seen a team mature over the last six months and today they hit their high peak.
"It's going to go right to the end, Chelsea and Arsenal going really well. We've beaten a strong Liverpool side playing good football."
Liverpool hopes to face United again this season _ in May's Champions League final. Benitez first has to overcome Arsenal in the quarterfinals, while United faces AS Roma.
