Liverpool midfielder Javier Mascherano could face a lengthy ban after being sent off against Manchester United for dissent, a Football Association (FA) spokesman said.

Mascherano, already on one yellow card, protested to referee Steve Bennett over his booking of team-mate Fernando Torres only to be shown a second yellow himself and then the red just before half-time with Liverpool losing 1-0. The Argentina international then went from a show of bemused surprise to outright anger and tried to continue his protest but was forcibly ushered from the field by Liverpool players and staff and calmed down by manager Rafa Benitez.

The dismissal carries an automatic one-match suspension but the FA can sanction Mascherano further for his refusal to leave the pitch immediately.

"When the player refuses to leave the field promptly, we do have mechanisms (for further punishment)," FA press officer Andrin Cooper said.

Mascherano said yesterday that he still did not understand why he had been shown a red card.

"I do not know why I was sent off," he was quoted as telling the Liverpool Echo.

"I asked the referee what was happening. I did not swear, I was not aggressive and I did not confront him.

"So when he showed me the second yellow card and sent me off I could not believe it."

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