Record winners Real Madrid and title holders Manchester City played to a thrilling 3-3 draw while Harry Kane continued to haunt Arsenal in their 2-2 with Bayern Munich in the Champions League quarter-finals on Tuesday.
City led early from Bernardo Silva's clever free-kick and went back on top at 3-2 from Josko Gvardiol in the 71st, five minutes after a stunner from Phil Foden.
But Real fought back twice in an epic 200th Champions League match of their coach Carlo Ancelotti which went back and forth.
They went 2-1 up within 12 minutes after Silva's opener when Ruben Dias deflected Eduardo Camavinga's shot into his own net and Rodrygo scored on the counter for 2-1, and Federico Valverdo was on target for the final score in the 79th.
"I think that goal, to equalise, lifts us quite a bit for the second leg," Valverde told Movistar.
"We need to be fuelled by a sense of revenge and go to Manchester full of hunger to qualify for the semi-final. Overall this was a great football match."
City's Gvardiol told TNT Sports: "What a game. First time for me to play here at this stadium, amazing atmosphere and we take the result and look forward to the game at home."
In London, Bukayo Saka fired Arsenal ahead in the 12th, their former player Serge Gnabry levelled in the 18th, and ex-Tottenham great Kane netted for the sixth time at Emirates Stadium with a 32nd-minute penalty to put Bayern 2-1 up.
However, Leandro Trossard salvaged a draw for the hosts with 14 minutes left.
"This has been a big game in my career, being at Tottenham for so many years. I'm just happy to be able to put the penalty away and help the team," Kane told Prime Video.
"It wasn't an easy game. Arsenal are a really good team. They're top of the Premier League right now so we had to dig deep at times but it's a good result and hopefully we can make the difference at home."
The return legs with all to play for are next week in Manchester and Munich, with the winners meeting in the semi-finals.
The matches took place amid beefed up security after an Islamic State terror threat via a media outlet linked to the group.
That will also concern the other first leg matches on Wednesday: Paris Saint-Germain v Barcelona and Atletico Madrid v Borussia Dortmund.
The 14-times champions Real and City crossed swords in the 2022 and 2023 semi-finals, with Real edging through two years ago in dramatic fashion while City prevailed 5-1 on aggregate last term with a 4-0 home win.
Real started their latest duel in the worst possible way.
Aurelien Tchouameni was booked in the opening minute for a foul on Jack Grealish which will see him suspended for the return leg, and Silva sunk the ensuing free-kick into the near left corner past a two-man wall and stranded goalkeeper Andrij Lunin.
The hosts were level after 12 minutes when Camavinga's speculative effort deflected off Dias into the far left corner.
And two minutes later Rodrygo took up a pass from Vinicius Junior, and poked home under pressure from Manuel Akanji as the ball rolled into the net past the left leg of goalkeeper Stefan Ortega after another slight deflection.
Real now controlled the action, with Vinicius Junior blazing over from a very promising position after the restart in the best of several chances.
They eventually paid the price as Foden, preferred by manager Pep Guardiola over Kevin de Bruyne, sensationally curled into the top left corner from the edge of the area, and Gvardiol then smashed City ahead again into the bottom right.
But that wasn't the end because Valverde found the left corner to put Real in a slightly better position for the trip to Etihad Stadium.
Arsenal had lost their last three knock-out ties against six-time winners Bayern but this time around they were Premier League leaders while Bayern were coming off back-to-back Bundesliga defeats which all but ended their title hopes.
Arsenal started well when Saka fired the opening goal in the 12th into the far corner past Manuel Neuer who was back from injury.
Ben White provided the assist and then should have scored himself shortly after, which backfired soon after as Gnabry beat David Raya from close range off Leon Goretzka for 1-1.
It got worse for the hosts when William Saliba brought down the lively Leroy Sane and Kane calmly sent Raya the wrong way with the ensuing penalty.
Bayern appeared in control after the break but substitute Trossard gave Arsenal some hope for the return leg, and they had a late penalty appeal turned down after contact between Neuer and Saka.
""It looked like a penalty to me, it looked like clear contact. We're not pleased but when you are 2-1 down at half-time you will take point at the end," Trossard said.
"We started so well. We could have scored two or three goals after taking the lead. You can see what kind of quality Bayern Munich have to hurt us."
