Spurs demolished London rivals Arsenal 5-1 in the semi-final of the Carling Cup on Tuesday but despite taking a first-half lead through Robbie Keane (24), United would not be stopped.

Carlos Tevez converted to level the scores after 38 minutes before Cristiano Ronaldo took full advantage of a clumsy handball by Michael Dawson, who was red carded, to score from the penalty spot.

The Portuguese scored a second two minutes from time - his 25th strike of the season - after a piece of goalkeeping Radek Cerny will not want to see again.

Earlier Kevin McNaughton provided the inspiration for Cardiff as they edged past Coca-Cola League Two outfit Hereford with a 2-1 win.

The Scottish defender produced a fine volley to break the deadlock in first-half injury-time and won a penalty which Steve Thompson converted in the 67th minute to give the Bluebirds a two-goal advantage.

Theo Robinson pulled a goal back for Graham Turner's side with 13 minutes left but the Championship outfit held on to secure their place in the last 16.

Under-fire Sheffield United boss Bryan Robson conjured arguably one of the sweetest results of his career as the Blades beat Manchester City 2-1 to clinch a place in the fifth round,

They forged a first-half lead courtesy of goals from Luton Shelton and Jon Stead.

Rising teenage star Daniel Sturridge gave City hope with a stunning volley three minutes after his arrival as a half-time substitute, but United were barely troubled beyond that.