Warnock wants answers

Television replays showed home defender Gabriel Heinze got nowhere near the ball when he launched into a second-half tackle on speedy Blades striker Luton Shelton, yet referee Rob Styles waved away the visitors' spot-kick claims.

Had the decision gone in favour of the Blades, Heinze would surely have been sent off as well and Warnock said: "I will be seeking clarification. Rob said he couldn't 100% give a penalty. But surely he should have looked at the linesman so between them they get it right."

He added: "Why can't you consult the linesman? What is the point in him being there?

"I don't understand it. At times, you need to use your linesman as another pair of eyes."

In fairness, Warnock admitted the decision may not have made that much difference to the outcome.

However, it did come as welcome relief to United given they could hardly afford to lose Heinze to suspension at a time when their defensive resources are so badly stretched.

When Patrice Evra hobbled off following a woeful first-half challenge by Colin Kazim-Richards, Sir Alex Ferguson's men were without seven senior defenders, including Rio Ferdinand.

Yet, even with midfielders Darren Fletcher and Kieran Richardson occupying the full-back roles, United still emerged victorious thanks to goals at the beginning of each half from Michael Carrick and Wayne Rooney.

Rooney is now up to 20 goals this season, just one behind star man Cristiano Ronaldo.