Atletico Madrid came from a goal down to beat 2004 Champions League finalists Monaco 2-1.
With just 18 minutes on the clock, Samuel Grandsir put the Principality ahead, sending home fans into raptures.
But that man Diego Costa brough Atletico back into it just past the half-hour mark after being set-up by Antoine Griezmann.
And in first-half injury time Jose Gimenez headed home Koke’s cross to complete the comeback.
The visitors had the stronger start and dominated with a high press that suffocated Monaco in the early stages.
Costa came close of opening the scoring after only six minutes following a combination with Griezmann, but his curled shot ended just wide of Diego Benaglio’s post.
Grandsir’s pace and runs caused some trouble, though, and he took advantage of a lapse of concentration in Atletico’s back four to break the deadlock.
Djibril Sidibe launched the move down the right flank and crossed for Radamel Falcao, who ran into the box and found Grandsir with a cutback pass that created panic in the area.
Angel Correa and Saul Niguez could not clear the ball and the 22-year-old winger slotted home from close range with his right foot.
Atletico pushed hard for an equaliser and was rewarded after a string of one-touch passes culminated in Costa’s goal in the 32nd minute.
Griezmann provided the assist with a subtle pass near the edge of the box that Costa collected before beating Benaglio.
Atletico dominated the remainder of the first half and took the lead from a corner just before the interval as Gimenez jumped higher than Falcao and Kevin N’Doram score with a powerful header.
Galatasaray returned to the Champions League in style on Tuesday, beating Lokomotiv Moscow 3-0.
After spending two seasons outside Europe’s premier club competition, the Turkish champion beat its Russian counterpart with high-tempo tactics and swift counterattacks in the Group D game.
Garry Rodrigues gave Galatasaray the lead in the ninth minute with a low hard shot from just outside the penalty area. Lokomotiv keeper Guilherme got a hand to the ball, but couldn’t stop it.
Eren Derdiyok doubled Galatasaray’s lead in the 67th when he curled a free kick around the Lokomotiv wall. Only Guilherme’s outstretched hand stopped Rodrigues making it 3-0 on a breakaway in the 75th.
Galatasaray midfielder Badou Ndiaye was sent off in the 87th after earning a second yellow card for a late tackle on Anton Miranchuk.
Selcuk Inan scored Galatasaray’s third from the penalty spot in stoppage time after Guilherme brought down Emre Akbaba on a counter-attack.
Porto and Schalke drew 1-1 in the other game in Group D.
Christian Pulisic celebrated his birthday by scoring on his return from injury to give Borussia Dortmund a late 1-0 win at Club Brugge in the Champions League on Tuesday.
The 20-year-old American, who hadn’t played since Aug. 26 due to muscular problems, came on with around 20 minutes remaining and scored in the 85th when Matej Mitrovic’s attempted clearance rebounded off his shin and looped in over Brugge goalkeeper Karlo Letica.
Red Star Belgrade ground out a 0-0 home draw against Napoli on the Serbian side’s Champions League debut as their goalkeeper Milan Borjan made a flurry of telling saves in a pulsating Group C clash.