Everton were taught a lesson by Atalanta as they crashed to a 3-0 defeat in their Europa League group-stage opener.
Atalanta opened the scoring in the 27th minute, with Everton failing to deal with a corner and Andrea Masiello firing home the loose ball.
The Serie A side made it two in the 41st minute as Alejandro Gomez bent a fine strike into the far corner, before Bryan Cristante added a third on the stroke of half-time as he slotted past Maarten Stekelenburg.
Also in Group E, Sardinero Adrian scored a last-minute equaliser as Apollon Limassol secured a 1-1 draw against Lyon.
Memphis Depay broke the deadlock for Lyon, slotting home a penalty in the 53rd minute, but Adrian popped up deep into injury time to claim a point for the Cypriot side.
Andre Silva scored a hat trick as AC Milan eased to a 5-1 victory over Austria Vienna.
Milan came firing out of the traps with two goals inside the first 10 minutes as Hakan Calhanoglu rifled a strike into the top corner, before Andre Silva slotted home Calhanoglu's pass.
Silva added a third on 20 minutes after linking up with Calhanoglu again before Vienna pulled one back just after the restart through Alexandar Borkovic's header.
But Silva restored Milan's three-goal advantage when completing his hat trick in the 56th minute and Suso then made it five in the 63rd minute with a long-range strike.
Elsewhere in Group D, AEK Athens edged Rijeka with a 2-1 victory as Lazaros Christodoulopoulos scored the deciding goal.
In Group A, Villarreal secured a 3-1 win over Astana.
The Spanish side edged ahead inside the 16th minute through Nicola Sansone, only for Yuriy Logvinenko to equalise in the 68th minute, before Cedric Bakambu and Denis Cheryshev both scored inside two minutes to swing the game back to Villarreal.
In the same group, Tomas Necid scored for Slavia Prague as they defeated Maccabi Tel-Aviv 1-0.
Braga came from behind to beat Hoffenheim 2-1 in Group C.
Wagner opened the scoring for Hoffenheim, heading home Pavel Kaderabek's cross, only for Joao Teixeira to level the score just before the half-time whistle with a header of his own and Dyego Sousa to turn the game around with a strike in the second half.
Istanbul Basaksehir, meanwhile, played out a goalless draw with Ludogorets Razgrad.
In Group B, Young Boys drew 1-1 with Partizan Belgrade, while Dynamo Kiev dismissed Skenderbeu Korce 3-1.
And in Group F, Copenhagen drew 0-0 with Lokomotiv Moscow, with Zlin doing the same against Sheriff Tiraspol.