Valencia scored twice in added-time to put one foot in the Europa League semi-finals with a 3-1 win over local rivals Villarreal at El Madrigal, while Benfica have the advantage against Eintracht Frankfurt.
Daniel Wass struck in the first minute of added time to put Valencia in the driving seat ahead of the second leg at the Mestalla, before Goncalo Guedes grabbed his second of the match to leave Villarreal facing an uphill task.
Both sides were awarded penalties in a pulsating first half, with former Arsenal midfielder Santi Cazorla cancelling out Guedes' opener.
Benfica's 19-year-old forward Joao Felix became the youngest player to score a Europa League hat-trick as he led them to a 4-2 win over 10-man Eintracht Frankfurt in their quarter-final first leg on Thursday.
The Bundesliga side were in danger of being blown away when Benfica went 4-1 ahead shortly after halftime but a second away goal by substitute Goncalo Paciencia left the tie more finely balanced for next week's return.