Villarreal took a big step towards reaching the Europa League last four after a first-half penalty from forward Gerard Moreno gave them a 1-0 win at Dinamo Zagreb in their quarterfinal first leg on Thursday.
The Spanish side will head into the return leg as favourites and should they advance, they will face either Arsenal or Slavia Prague for a berth in the May 26 final in Gdansk.
Villarreal coach Unai Emery, who won three successive Europa League titles with Sevilla, praised his side's clinical performance.
"It was a tough game against a side full of talent who has just knocked Spurs out," he said.
"We played a good game, adjusting ourselves up top and not allowing ourselves to be exposed on the counter, either. We need to be prudent - it's just 90 minutes that we have won, there's still the second leg to come."
Dinamo staged a major upset to reach the last eight with a 3-2 aggregate win over Tottenham Hotspur but never looked like repeating a stunning 3-0 second-leg victory over the Premier League side as they lacked cutting edge.
Mislav Orsic, who bagged a hat-trick against Spurs, had the ball in the back of Villarreal's net in the 26th minute but his effort was disallowed for offside and that was the closest Dinamo came to scoring.
The visitors always looked more likely to break the deadlock and Moreno sent goalkeeper Dominik Livakovic the wrong way with a coolly taken spot-kick after Kevin Teophile-Catherine handled his cross.
A deflected shot by Manuel Trigueros drew a fingertip save from Livakovic as the visitors found gaps in Dinamo's half with the home side throwing men forward in the closing stages.
Dinamo coach Damir Krznar conceded his side were fortunate to have only a one-goal deficit.
"We were below par and we should consider ourselves lucky to be only 1-0 down in the tie," he said.
"We're still in with a chance. We dominated the first half but conceded shortly before the break while we faded away in the second. We were impatient and failed to contain Villarreal from keeping possession."