PORTO, Portugal (AP)

Cristiano Ronaldo scored a spectacular long-range goal yesterday to give Manchester United a 1-0 win over FC Porto and a spot in the Champions League semi-finals with a 3-2 aggregate victory.

Ronaldo began his run from just inside the Porto half in the sixth minute and sent a rising shot from 40 yards past diving goalkeeper Helton and into the top corner of goal in the second leg of the quarter-finals.

"To do it at that point in the game gave us a real platform to go into the game," United manager Alex Ferguson said. "We wanted to start the game quickly, with good tempo ... but to get a start like that, no one can expect it, no one can expect that type of goal."

A fantastic semi-final

Man United will next play English rival Arsenal in the semi-finals after the Gunners beat Villarreal 3-0 to advance 4-1 on aggregate.

"It's two good football teams so it should be a fantastic semi-final," Ferguson said. "We'll look forward to it."

United showed better discipline to start than at the first leg at Old Trafford and controlled the play at the Stadium of Dragon from the fourth minute when goalkeeper Edwin van der Saar stopped winger Hulk's low shot.

"We tried to change and spread the team around the field and hope Manchester would make some mistakes," Jose Gomes, who replaced suspended coach Jesualdo Ferreira, said through a translator.

"They had to chase. That early (goal) had them on the back foot. I don't think they made any chances in the match," Ferguson said. "(We) defended very, very well and that was the key to it really, because if we get back to that foundation of not giving away goals then we can do well."

Champions League

Helton stepped up to clear a dangerous centering pass, and then denied Dimitar Berbatov at the start of the second half as Porto looked for the equaliser that would put them through to the semi-finals for the first time since 2004, when they had eliminated United on their way to winning the Champions League.

Hulk, unable to generate from the flank, tried to score with a free kick from the edge of the area in the 58th but it swerved directly at Van der Sar.

Porto had several other scoring chances, but Mariano, Rolando and substitute Ernesto Farias couldn't score the equaliser.

"We feel very bad. You can understand our emotions. We feel that wasn't a very just result today," Gomes said. "They scored one goal today and it was scored by the best player in the world."