In a meeting of two former European champions in crisis, Ajax and Marseille drew 3-3 in "a crazy game" while Liverpool and West Ham were also winners in the opening round of Europa League group games.
In Amsterdam, Ajax, who have won just two games all season and sit 12th in the Dutch league met Marseille who are third in Ligue 1.
However, after a meeting between Marseille fan representatives and the club's hierarchy reportedly turned nasty, coach Marcelino, only appointed in June, resigned on Tuesday after just seven games in charge.
On Thursday, both teams tore into the game.
"It could have been 6-6," said Ajax coach Maurice Steijn. "I don't want to talk about a crisis, I saw a great match in a full stadium."
Liverpool, playing in the Europa League for the first time since finishing runners-up in 2016, went behind for the fourth time in five matches this season but fought back to beat LASK 3-1 in Linz.
They fell behind to a 14th-minute rocket from Florian Flecker but Darwin Nunez levelled with a 55th-minute penalty kick after Luis Diaz was brought down.
After 61 minutes, Klopp started to replace teenagers with regular starters and within two minutes they were ahead when Ryan Gravenberch, on his full debut, burst down the right and crossed low for Diaz to score from close range.
Two minutes from the end Mohamed Salah, a second-half replacement, poked home a third.
West Ham, who won the Conference League last season, also hit back to beat visiting Serbian club TSC Backa Topola 3-1
Brighton, making their European debut in the Europa League, and Aston Villa returning to Europe, after 12 years, in the Conference League, both fell behind early and although they each equalised twice, lost 3-2.
In Brighton, Djibril Sidibe put AEK ahead with a bullet header from 13 yards.
Brighton twice levelled with Joao Pedro penalties. AEK twice regained the lead when sudden deflections in the rain opened up chances. Mijat Gacinovic buried one and Ezequiel Ponce tucked home the winner.
Elsewhere in the Europa League, Romelu Lukaku earned last year's beaten finalists Roma a 2-1 victory at Sheriff in Moldova.
Abdallah Sima scored the only goal as Rangers beat Real Betis 1-0 in Glasgow.
Bayer Leverkusen crushed Swedes Hacken 4-0, Rennes cruised past Maccabi Haifa 3-0 in France, Spaniards Villarreal lost 2-0 to Panathinakos in Greece. (AFP)