Schalke '04 was the unlikely trailblazer on a night of 11 Champions League goals when it thumped Inter Milan 5-2 to become the first team ever to score five in one match against the reigning European Cup holder.
In Tuesday's other high-scoring game, Real Madrid beat Tottenham Hotspur 4-0 at the Bernabeu stadium to inflict Spurs' record defeat in European competition and leave the first two quarterfinals virtually over before next week's second legs.
Spurs faced an almost impossible task for most of the match after striker Peter Crouch was sent off in the 15th minute.
The result left Real coach Jose Mourinho looking ahead to a possible semifinal against arch-rival Barcelona, which host Shakhtar Donetsk in its first leg on Wednesday.
“If we have to play against Barcelona we have to train well with 10 men because every time I go there, it's the same story,” he told Sky Sports .
With Schalke and Real all but through, Tottenham and Inter must stage incredible comebacks to make the last four after both finished with 10 men and were punished for defensive lapses.
Inter will travel to Germany next week knowing it has almost certainly lost the crown it won under Mourinho, while Spurs have a mountain to climb at White Hart Lane.
The game at the San Siro was the second in the Champions League to produce seven goals this season after Inter beat Spurs 4-3 there in the group stage.
This time though Schalke, which has had a mediocre season in the Bundesliga and replaced coach Felix Magath with Ralf Rangnick three weeks ago, recovered from conceding a first-minute goal to Inter and stormed back for a stunning win.
The Italians went ahead in the first minute when Schalke 'keeper Manuel Neuer ran out to head clear and Dejan Stankovic calmly volleyed it into the net from just inside Inter's half.
Joel Matip equalised and, although Diego Milito briefly restored Inter's lead, two goals from Edu, one from Raul and an Andrea Ranocchia own goal put Schalke in control of the tie.
Inter's night got worse when defender Cristian Chivu was sent off for his second yellow card just past the hour mark.
Trouble started for Spurs before kick-off when winger Aaron Lennon was taken ill after the teams left their dressing rooms.
The London side quickly found itself a goal down to an Emmanuel Adebayor header after four minutes and a man down after Crouch's dismissal for a second yellow card 11 minutes later.
Adebayor, who made a habit of scoring against Spurs when he played for its arch-rival Arsenal, doubled Real's lead with a second header before Angel Di Maria and Cristiano Ronaldo completed the rout in the closing stages.
The results: Real Madrid 4 (Adebayor 4, 57, di Maria 72, Ronaldo 87) bt Tottenham Hotspur 0; Inter Milan 2 (Stankovic 1, D. Milito 34) lost to Schalke ‘04 5 (Matip 17, Goncalves 40, 75, Raul 53, Ranocchia 57-og).
