It was a brilliant goal, set up by Cesc Fabregas that earned Arsenal the second-half equalizer. Adebayor chested Fabregas' pass and scored with a scissors kick to give the Gunners the valuable away goal.
Marcos Senna had scored for Villarreal in the 10th minute on a long-range shot.
Arsenal goalkeeper Manuel Almunia and defender William Gallas were injured in the game.
Almunia landed awkwardly on his right ankle early in the game and had to be replaced by Lukasz Fabianski in the 28th minute. The Spaniard could miss three weeks.
Gallas collided with Rossi and went off two minutes before halftime with a knee injury that could sideline him for the rest of the season.
Fabianski was quickly tested and made two big saves to keep the game close in the first half.
"When they scored an early goal," said Arsenal manager Arsene Wenger, "to get in at 1-0 at halftime was not bad because we could reorganize a bit and bounce back in the second half. We are mentally strong, resolute ... we never give up. We had a few opportunities to score a second goal that we didn't take."
April 7 in Villarreal
Villarreal 1 Arsenal 1. Goals: Senna 10; Adebayor 66.
Villarreal -- D.Lopez, A.Lopez, Godin, Rodriguez, Capdevila, Cani (Fernandez 46), Senna, Eguren, Ibagaza (Franco 78), Llorente (Pires 70), Rossi.
Arsenal -- Almunia (Fabianski, 28), Sagna, Toure, Gallas (Djourou 43), Clichy, Denilson, Song, Fabregas, Walcott (Eboue 78), Nasri, Adebayor.
Referee: Tom Henning Ovrebo (Norway).