FC Porto and Arsenal scored crucial away goals on Tuesday night, giving both clubs the edge heading into the second leg of the Champions League quarterfinals next week.

Porto got a late equalizer from substitute Mariano Gonzalez in its 2-2 draw at defending champion Manchester United, while Emmanuel Adebayor scored in the second half to give Arsenal a 1-1 draw at Villarreal.

The second legs will be played April 15. The winners will play each other in next month’s semifinals.

Gonzalez scored Porto’s equalizing 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.

Meanwhile, 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 beautiful bicycle kick.

Arsenal may have a slight advantage heading into the second leg, but the English club may have to play without defender William Gallas. The Associated Press reported that 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, the NJ-born Giuseppe Rossi, 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 minute.