Manchester United have it all to do to reach the semi-finals of the UEFA Champions League after being held 2-2 at home by Porto.

The holders appeared to have stolen another dramatic Old Trafford victory when substitute Carlos Tevez turned home Wayne Rooney's flick-on at the near post on 85 minutes.

But a minute from time, Porto substitute Mariano Gonzalez was left unmarked at the far post to give the 2004 winners a fine chance of dumping out the reigning champions.

Porto, who knocked out United in the last 16 five years ago, enjoyed a dream start on their return to Old Trafford when Cristian Rodriguez seized on a poor clearance from Jonny Evans to rifle a crisp shot past Edwin van der Sar after just four minutes.

United were level in the 15th minute when Wayne Rooney pounced on a dreadful back-pass from Bruno Alves to lift a shot over the exposed Helton.

The Red Devils had been poor for most of the first half, but improved after the break as they streamed forward in search of a winner.

The breakthrough came five minutes from time when Tevez reacted sharply to Rooney's flick from Gary Neville's throw-in to seemingly give United a vital advantage.

But the hosts reckoned without a plucky Porto fight-back as Lisandro Lopez's cross was helped on to the unmarked Gonzalez and he lifted the ball past the onrushing Van der Sar.

And to become the first team to successfully defend the Champions League, United must also become the first English team to win at Porto's Estadio do Dragao in the quarter-final second leg next Wednesday.

Sky Sports