Liverpool and Villarreal played out a tightly contested game at El Madrigal.
Liverpool slipped to a 1-0 defeat to Villarreal, leaving themselves with plenty of work to do to get to the Europa League final.
The Reds could not break down a stubborn Villarreal defence, with their decision not to start a striker proving costly.
Both Daniel Sturridge and Christian Benteke were left on the bench, with Roberto Firmino played as a false nine.
The Brazilian was not able to reproduce his earlier performances this season in the position, which included him scoring a brace against Arsenal at Anfield.
Former Manchester United defender Phil Neville told The BBC he was particularly disappointed with Firmino's display at El Madrigal.
He said: "I've been disappointed with Roberto Firmino. Every time Liverpool give the ball away it seems to be him doing it. He's been so loose in possession."
Firmino completed 80 per cent of his passes, touching the ball 48 times during the clash. He had one shot at goal, and did not create any chances.
Next time the two teams face off, Firmino is more likely to back in his usual position in midfield, able to dictate the play a little easier.