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 United were also winners Thursday in the opening round of Europa League group games.
Liverpool fell behind for the fourth time in five matches this season but fought back to beat LASK 3-1 in Linz to make Jurgen Klopp the first coach to win 50 European games at the Merseyside club.
West Ham, who won the Conference League last season, also hit back to beat visiting Serbian club TSC Backa Topola 3-1.
Brighton and Hove Albion, 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 equalized twice, lost 3-2.
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 Garcia Toral, only appointed in June, resigned Tuesday after just seven games in charge.
Thursday, both teams tore into the game.
Ajax carved open the visiting defence in the first 20 minutes and took a two-goal lead with goals by Carlos Borges and Steven Berghuis.
"I knew the players would get back into the game and we'd score the goal that would set us free. It was a crazy game, but I also think we were in control," said interim Marseille coach Jacques Abardonado.
Jonathan Clauss and Pierre-Emerick Aubameyang hit back before half time.
As both sides peppered the opposing goals, Kenneth Taylor restored the home edge but Aubameyang levelled again with 12 minutes left.
Marseille finished with 25 attempts on goal.
"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."
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.
"We can improve but it's difficult to accept this defeat," said Brighton coach Roberto De Zerbi.
"I can't be happy when we win at Old Trafford and sad today with a good performance."
"We didn't show as much experience as AEK."
Liverpool, playing in the Europa League for the first time since finishing runners-up in 2016, changed their entire starting 11 away to LASK.
They fell behind to a 14th-minute rocket from Florian Flecker.
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.
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.
"I'm really, really happy, because I said before, I knew it would be difficult and it was difficult," said Klopp.
"A well-deserved win in the end, and that's it."
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 and Spaniards Villarreal lost 2-0 to Panathinaikos in Greece.
RESULTS
Group A
West Ham 3 (Petrovic 66-og, Kudus 70, Soucek 82) Backa Topola 1 (Stanic 48)
Olympiakos 2 (Kaabi 40, 75) Freiburg 3 (Sallai 9, Grifo 45+7-P, Philipp 86)
Group B
Ajax 3 (Borges 9, Berghuis 20, Taylor 52) Marseille 3 (Clauss 23, Aubameyang 38, 78)
Brighton 2 (Pedro 30-P, 67-P) AEK Athens 3 (Sidibe 11, Gacinovic 40, Ponce 84)
Group C
Sparta Prague 3 (Krejci 20, 25, Vitik 67) Aris Limassol 2 (Kokorin 11-P, Babicka 90)
Rangers 1 (Sima 68) Betis 0
Group D
Atalanta 2 (Ketelaere 49, Ederson 66) Czestochowa 0
Sturm Graz 1 (Boving 58) Sporting 2 (Gyokeres 76, Diomande 84)
Group E
Saint-Gilloise 1 (Amoura 69) Toulouse 1 (Dallinga 45+3-P)
LASK 1 (Flecker 14) Liverpool 3 (Nunez 56-P, Diaz 63, Salah 88)
Group F
Rennes 3 (Blas 1, Truffert 31, Yildirim 56) Maccabi 0
Panathinaikos 2 (Ioannidis 38, Sporar 78) Villarreal 0
Group G
Servette 0 Slavia Prague 2 (Masopust 32, Ogbu 59)
Sheriff Tiraspol 1 (Tovar 57) Roma 2 (Paredes 45+4, Lukaku 65)
Group H
Leverkusen 4 (Wirtz 10, Adli 16, Boniface 66, Hofmann 70) Hacken 0
Qarabag 1 (Andrade 56) Molde 0