Daizen Maeda was sent off as Celtic suffered a thumping 6-0 defeat against Atletico Madrid, leaving them adrift in their Champions League group.
Celtic were already trailing Antoine Griezmann’s deflected goal when Maeda saw a yellow card upgraded to a red following a VAR review midway through the first half at the Estadio Metropolitano.
Alvaro Morata and Griezmann both netted doubles, and Samuel Lino and Saul Niguez scored as Atletico capitalised on their numerical advantage in devastating fashion with a string of spectacular second-half goals.
The damage was done when Maeda left a foot dangling as he went in for a 50-50 challenge with Mario Hermoso, who rolled around on the floor after being caught on the shin as he followed through.
Atletico boss Diego Simeone and six or seven of his backroom staff raced off the bench after the incident, sparking an angry reaction from Celtic manager Brendan Rodgers when the referee was called to his monitor.
Rodgers was booked for dissent as Simeone dragged one of his colleagues back from confronting the Celtic boss.
Celtic are now five points adrift of third-placed Feyenoord, and, although not eliminated, they will need to beat Lazio and the Dutch side in their final two games while relying on favours from Atletico to have any hope of extending their European run beyond Christmas.
They will travel to Rome for the November 28 game with Lazio without Maeda and fellow winger Luis Palma, who picked up his third yellow card of the campaign when he was booked for dissent.
Rodgers picked the same team that played the bulk of the 2-2 draw with Atletico two weeks ago. That meant Paulo Bernardo came in for David Turnbull, who had scored in each of Celtic’s last two league games.
Griezmann started in midfield and opened the scoring in the sixth minute after Celtic twice put themselves under pressure.
Joe Hart sliced a punch clear under no pressure following a corner, and Callum McGregor headed a poor clearance straight to Griezmann.
The Frenchman shot from 20 yards, and a deflection off Cameron Carter-Vickers took the ball out of Hart’s reach and into the bottom corner.
Palma forced a save with what would prove to be Celtic’s only effort on goal as they tried to respond, and McGregor soon saved his side by blocking Rodrigo Riquelme following a counter-attack.
The red card soon followed, and although Atletico goalkeeper Jan Oblak saved brilliantly from Morata’s sliced clearance, the rest of the game was an exercise in defending for Celtic.
Griezmann twice, and Nahuel Molina threatened before the France international’s diagonal ball exposed Celtic in first-half stoppage time. Jose Maria Gimenez headed across the goal for Morata to slide in and convert from close range.
The onslaught continued, even before the interval, when Hart saved Angel Correa.
Rodgers brought on Oh Hyeon-gyu for Palma at halftime as he maintained his 4-3-2 formation throughout.
Griezmann continued to threaten on regular occasions, and Gimenez headed off the bar before the Frenchman netted with a scissors kick on the hour mark after meeting Alistair Johnston’s headed clearance.
Substitute Lino took a step inside Johnston and curled in a brilliant fourth six minutes later.
Correa hit a post before Morata took a touch on the edge of the box and lashed a shot into the roof of the net in the 76th minute.
Celtic finished the game with a midfield of Turnbull, Odin Thiago Holm, and Tomoki Iwata, and they lost a scrappy goal in the 84th minute when Niguez finished from close range.
Their heaviest European defeat had come in Spain under Rodgers seven years ago, and Atletico could not emulate that 7-0 victory amid further pressure.