Manchester United manager Sir Alex Ferguson believes Liverpool's Javier Mascherano deserved a red card for his first half challenge on Antonio Valencia in the 2-1 win at Old Trafford on Sunday.
Valencia was brought down in the 10th minute by Mascherano when Liverpool were a goal up after Fernando Torres struck earlier and Ferguson thought the Argentine should have been sent from the pitch, his view differing completely from Reds boss Rafael Benitez.
"I thought it was a red card," he said.
"There was no way (Jamie) Carragher could get across and stop Valencia from shooting (after Mascherano) - he is too quick for Carragher to get across.
"The law is if you stop someone from having a goalscoring opportunity it is a red card. Not today.
"The referee was right, he tugged him down. He didn't bring him down outside the box; he didn't go down until he was inside the box. The decision (of a penalty) was correct."