Manchester:FC Porto and Arsenal scored crucial away goals, giving both teams the advantage heading into the second leg of the Champions League quarterfinals next week.
Porto got a late equaliser from substitute Mariano Gonzalez in its 2-2 draw at defending champion Manchester United on Tuesday, and Emmanuel Adebayor scored in the second half to give Arsenal a 1-1 draw at Villarreal.
The second legs will be played April 15, and the winners will play each other next month in the semifinals.
Gonzalez scored Porto's equalising goal in the 89th minute, four minutes after Carlos Tevez had put United ahead 2-1 at Old Trafford.
Lucho Gonzalez's cross from the right was left by Gary Neville and Mariano brought it down with his chest before shooting past United goalkeeper Edwin van der Sar.
"Getting the goal the way they did we should really have defended that. It was a bad goal to lose," United manager Alex Ferguson said. "It will be a difficult game now over in Porto without question."
Tevez thought he had given United the lead for good only minutes earlier, lifting the ball into the net when Wayne Rooney's heel flicked on Neville's throw in.
In the first half, United trailed for the first time in its title defense in the fourth minute when Jonny Evans' poor clearance allowed Cristian Rodriguez to put Porto ahead. But the visitors also had some sloppy defending, and Rooney took advantage of it to equalise in the 15th by pouncing on a lax backpass from Bruno Alves.
"The score is a good score but nothing is sorted out yet," Porto coach Jesualdo Ferreira said through a translator.
"But it means we can go to the Dragon (stadium) and confront them."
Arsenal got its away goal in the 66th minute when Adebayor chested a long ball from Cesc Fabregas to the right of the area and beat Diego Lopez with a bicycle kick.
Villarreal had taken the lead in the 10th when Marcos Senna's swerving shot from 20 meters (yards) evaded diving goalkeeper Manuel Almunia and landed inside the top corner.
Fabregas had also set up both of Adebayor's goals in Saturday's 2-0 win over Manchester City, which marked both players return from lengthy injury spells.
In the 70th, Robert Pires came on to face his former team for the first time since leaving London in 2006, and Villarreal began to respond with better chances. Guille Franco, however, missed two good chances in the last 10 minutes and Senna sent a hard shot toward goal in the 80th but is just missed the top corner.
"I think it was rather unjust to come away with just a draw," Villarreal coach Manuel Pellegrini said. "We created at least four clear chances in the first half and I don't think Arsenal created more chances apart from the goal during the 90 minutes."
Arsenal may have the advantage heading into the second leg, but the English team may have to play without defender William Gallas.
The France international could be out for the rest of the season after damaging knee ligaments in the first half. He went down after colliding with Villarreal striker Giuseppe Rossi late in the first half and stayed on the field for several more minutes before limping off and being replaced by Johan Djourou in the 43rd.
"It looks quite serious," Arsenal manager Arsene Wenger said.
"We have to asses it tomorrow but the first signs don't look too good."
Goalkeeper Manuel Almunia is also likely to miss the second leg.
He hurt his ankle after coming out of his area to clear an early Villarreal long ball.
"It could be a couple of weeks (out)," Wenger said. "I'm not a doctor but the information I got from medical staff says it looks like that."
The last time the two teams met, Arsenal goalkeeper Jens Lehman saved Juan Roman Riquelme's late penalty to put the Gunners into the Champions League final in Paris, where the English team lost to Barcelona 2-1.
Five-time European champion Liverpool will host Chelsea in the first leg of the quarterfinals tomorrow, while Bayern Munich visits Barcelona. The second legs will be played next Tuesday.
The final is scheduled for May 27 in Rome.