Two goals in the space of four minutes just before the break was enough for Villarreal to fightback and earn a draw at home to Slavia Prague.
Early strikes from Tomas Necid and Danny had seemed to give the Czech visitors control in the tie but Manuel Trigueros and Carlos Bacca responded for the hosts before the break.
Necid opened the scoring with a well-placed header before veteran Portuguese forward Danny doubled the lead after being picked out by winger Jan Sykora inside the box.
However, eleven minutes Trigueros’s well-timed run and finished halved the deficit before a typical quick-thinking and close-range finish from Bacca after a blotched clearance levelled the ties.
The result extends Villarreal’s unbeaten start under new Coach Javier Calleja to four matches in all competitions as both sides sit top of the group on five points, one clear of third-placed Astana.