Fergie has urged Webb and his assistants to keep a watchful eye on the Uruguayan striker.
Boss Fergie said: “The lad is laden with controversy. I don’t know whether he enjoys it or not but it is something we hope we don’t suffer from ourselves.”
But Kop chief Brendan Rodgers has highlighted how decisions went AGAINST his side when they last played United and saw Jonjo Shelvey harshly sent off.
United won with a disputed penalty at Anfield.
Rodgers said: “We hope we don’t have the decisions go against us that went for United in that game.
“A sending off and penalty cost us the game. I hope they don’t get the decisions that can influence the results.”