Hamburg  - A Cristiano Ronaldo wonder goal from all of 40 metres helped Manchester United beat Porto 1-0 Wednesday to book their place in the semi-finals of the Champions League.

United will now meet fellow English Premier League side Arsenal after goals from Theo Walcott, Emmanuel Adebayor and a Robin van Persie penalty ensured a 3-0 win over Spanish side Villarreal for the Gunners, who progress to the last four 4-1 on aggregate.

With Porto holding the advantage on the away goals rule after the quarter-final first-leg at Old Trafford finished 2-2, United needed to score to have any chance of progressing and Ronaldo duly obliged with his unstoppable strike after just six minutes.

Although Porto came close themselves five minutes before the break when Bruno Alves headed narrowly wide, United dominated position in the first period and could have gone two up on 43 minutes when John O'Shea headed a Ryan Giggs into the path of Nemanja Vidic but the Serbian defender sent the ball over the bar from five metres.

Porto started the second half the brighter and Mariano Gonzalez should have done better than heading tamely wide when allowed to rise unchallenged in the United area on 54 minutes.

Hulk fired a free kick straight at Edwin van der Sar four minutes later but the Dutch goalkeeper almost gifted Porto a goal when he badly misjudged a corner from the right but Rolando sent his header over from a tight angle.

Porto continued to press with time running out, with the best chance falling to Lisandro five minutes from time but his weak shot was easily saved by Van der Sar.

However, United hung on to become the first English side to win a competitive match at Porto and progress 3-2 on aggregate and set up a clash with Arsenal, who had a much easier time of it against Villarreal at the Emirates.

Arsenal only needed to keep a clean sheet to be certain of qualifying but the fans' nerves were settled after 10 minutes when Cesc Fabregas backheeled Emmanuel Eboue's pass into the path of Walcott, who clinically dispatched the ball past goalkeeper Diego Lopez to make it 1-0.

Adebayor made it 2-0 on the hour mark and any faint hopes Arsenal had of a comeback ended nine minutes later when Arsenal were awarded a penalty when Diego Godin was adjudged to have fouled Walcott in the area.

Sebastian Eguren subsequently saw red after picking up a second yellow card for protesting while before Van Persie slotted the spot kick home to make it 3-0.

In Tuesday's quarter-final matches, Chelsea drew 4-4 with Liverpool to progress 7-5 on aggregate while Barcelona drew 1-1 with Bayern Munich to prevail 5-1 on aggregate.

The semi-finals are scheduled for April 28 and 29 with the return legs on May 5 and 6. (dpa)