Tottenham's Jermaine Jenas has accused Howard Webb of "crumbling under pressure" after his controversial penalty award to Manchester United.Webb handed the champions a dubious penalty when they were trailing 2-0 against Spurs, with Heurelho Gomes deemed to have felled Michael Carrick, despite replays suggesting he made contact with the ball.Cristiano Ronaldo converted the penalty and United went on to score four further times to win 5-2.But Jenas believes the turnaround was set in motion by a moment of weakness."I think it was a case of a referee crumbling under the pressure at Old Trafford really," said the England midfielder."The atmosphere, the occasion, the importance of the match, a lot of factors take their toll when making decisions."One thing which struck me about it was that he didn't even think. It was like he'd already made his mind up when he came out for the second half that he was going to give something."I think he will definitely admit he got that one wrong. It was a very important moment in the season."