Substitute Adrian struck in stoppage time to give Villarreal a 1-0 Europa League semi-final first-leg win over Liverpool at El Madrigal on Thursday.
Adrian, who scored in Atletico Madrid's Champions League semi-final win over Chelsea in 2014, was on hand to potentially deal out further misery to a Premier League side, while Liverpool will need another inspired Anfield night next week.
Liverpool set pulses racing with a remarkable comeback and injury-time triumph over tournament favourites Borussia Dortmund in the previous round – a stark contrast to this largely cagey encounter.
Visiting manager Jurgen Klopp started without a conventional centre forward, leaving Daniel Sturridge as an unused substitute despite Divock Origi's injury absence and Liverpool lacked cutting edge despite a controlled display in midfield, led by the excellent James Milner.
It was left to fellow forward Adrian to crown a slick counter-attack – Bruno's lofted pass in behind Kolo Toure stylishly collected by Denis Suarez, who calmly rolled across goal to leave his team-mate with a simple finish.
Former Tottenham forward Roberto Soldado sent a bouncing shot across Simon Mignolet's goal and the Liverpool keeper plunged to his left in the 21st minute to keep out Tomas Pina's 20-yard drive.
Toure got in the way of a sweetly struck Bruno effort and Alberto Moreno regained his footing to deflect Mario Gaspar's follow-up behind.
Bruno was Villarreal's main source of creativity and he found Soldado for the striker to spin into space and curl wide right-footed three minutes before the break.
The hosts almost led a minute into the second half when Bakambu rose to above Dejan Lovren to head Jonathan dos Santos' corner against the outside of the post.
The play became increasingly listless as a scrappy content passed the hour, although it was soon Liverpool's turn to test the upright.
Firmino collected a measured pass from his captain, Milner, and fired a low shot goalwards that Asenjo did well to tip against the base of his near post.
A robust challenge from Lucas Leiva on Pina prompted a seemingly furious touchline confrontation between Klopp and opposite number Marcelino – order soon restored as the German embraced his opposite number with a trademark chuckle.
Adam Lallana was incorrectly flagged offside as he stole in behind the Villarreal defence and Eric Bailly's pursuit of the England international resulted in him hobbling from the field.
