Napoli took control of their Europa League tie against RB Salzburg with a comfortable 3-0 win at the Stadio San Paolo on Thursday.
The home side took the lead after just ten minutes when Dries Mertens capped off a wonderful team move by threading through Arkadiusz Milik who rounded the keeper and tapped home.
Carlo Ancelotti's side doubled their lead when Fabian Ruiz thundered home on the volley and just before the hour Jerome Onguene headed into his own net.
Villarreal and Dinamo Zagreb secured crucial first-leg wins on Thursday in the Europe League whilst two of the other early games, Sevilla v Slavia Prague and Eintracht Frankfurt v Inter Milan, ended all square.
Sevilla, who have won the Europa League three times, twice went ahead against Slavia Prague but were pegged back on both occasions in a pulsating 2-2 draw in Spain.
Wissam Ben Yedder put the home side ahead in the first minute and although Miroslav Stoch equalised with a deflected shot, Munir restored Sevilla's lead.
Alex Kral put the visitors level again six minutes before halftime when he turned a corner into the net.
Fellow Spaniards Villarreal had a happier evening in St Petersburg and will take a solid 3-1 lead into the second leg at home.
Villarreal, third bottom of La Liga, went ahead against Zenit after 33 minutes when Vicente Iborra headed home from a free kick but the home side took only two minutes to level thanks to Sardar Azmoun, whose quick thinking allowed him to stab home from close range.
The Spaniards, though, took control in the second half, with Gerard Moreno putting them 2-1 ahead after 64 minutes and Manu Morlanes added the third.
Bruno Petkovic scored a penalty for Dinamo Zagreb to give them a 1-0 home win over Benfica while in the only game between two former winners of the UEFA Cup, Eintracht Frankfurt drew 0-0 at home against Inter Milan.
It was the first time Eintracht, who have won seven of their eight Europa League matches this season, failed to score but at the other end they were thankful to their goalkeeper Kevin Trapp after he made a fine penalty stop from Marcelo Brozovic.
Valencia will take a 2-1 lead with them to Russia after beating Krasnodar at the Mestalla thanks to a first-half brace from Rodrigo.
Viktor Claesson scored the potentially crucial away match for the visitors.