Serie A leaders Napoli were beaten at home by RB Leipzig in the Europa League last 32, while Lazio went down at FCSB and Lyon triumphed at home against Villarreal.
With Borussia Dortmund, Arsenal, Atletico Madrid, Celtic and AC Milan all securing first-leg wins, the competition is stacked with talented teams and the knockout stages got under way on Thursday.
Maurizio Sarri rested Dries Mertens and named two goalkeepers among his seven substitutes, paying the price as Napoli lost 3-1 to Bundesliga high-flyers Leipzig, with Timo Werner scoring a brace of away goals in a crucial victory.
Marseille gave themselves a comfortable lead with a 3-0 defeat of Braga, while Sporting CP came from behind to win away to Astana.
Werner at the double against Azzurri
RB Leipzig carry a massive advantage with them into next week's return leg shocking the Serie A leaders at the Stadio San Paolo, despite Adam Ounas scoring his first European goal to give the hosts the lead.
Napoli's joy was short-lived, however, Werner restoring parity by capitalising on a smart dummy from Youssef Poulsen to tuck a composed finish beyond Pepe Reina.
Bruma then gave the Bundesliga outfit the lead on 74 minutes, finishing off an unselfish bit of play from Poulsen into an empty net as the visitors remained lethal on the break.
And Werner decisively struck again in the final minute of stoppage time, this time finishing off a pass from Emil Forsberg - the Sweden international making his first appearance of 2018 - leaving Napoli with a mountain to climb in a week's time.
Lazio were also beaten against the odds, Simone Inzaghi's men losing 1-0 in Bucharest thanks to a first-half goal from Harlem-Eddy Gnohere.
The Rome side were in Scudetto contention during the first half of the season but have lost form in dramatic fashion, losing four of their last five games in all competitions.
Depay boosts Lyon with late strike
A 3-1 victory at home to Villarreal gives Lyon a strong advantage ahead of next week's return leg in Spain, Memphis Depay scoring after coming off the bench.
Quickfire goals from Tanguy Ndombele and captain Nabil Fekir immediately after the interval had given Lyon a 2-0 lead but Pablo Fornals struck back to boost Villarreal's hopes before Depay's late impact.
Lyon's fellow Ligue 1 side Marseille also recorded a first-leg win, with Valere Germain scoring a double in a 3-0 victory against Portuguese side Braga.
But there was worse news for France's third entrant Nice, Racine Coly's red card proving a key moment in a 3-2 home defeat at the hands of Lokomotiv Moscow.
Mario Balotelli's brace put Nice in control but a Manuel Fernandes hat-trick ensured the Russians take a slender advantage in the tie after a sensational comeback.
Astana collapse at home
Kazakh side Astana made a great start in their game against Sporting CP, taking a seventh-minute lead thanks to Marin Tomasov's finish.
But the Portuguese side roared back with three goals in an eight-minute period following the interval, Bruno Fernandes getting the comeback started from the penalty spot.
Gelson Martins and Seydou Doumbia added further goals before Yuri Logvinenko was dismissed for a second bookable offence to cap a miserable match for the hosts.
Takumi Minamino scored deep in injury-time to earn Red Bull Salzburg a 2-2 draw away to Real Sociedad, while veteran striker Aritz Aduriz struck twice for Athletic Bilbao in a 3-1 win at Spartak Moscow.
The 37-year-old has now scored in five consecutive appearances in the Europa League, matching the record held by Radamel Falcao and Giuseppe Rossi.
Elsewhere, Partizan Belgrade and Viktoria Plzen drew 1-1, with the tie between AEK Athens and Dynamo Kiev in the Greek capital ending in the same scoreline.
