Pablo Duran initially looked to be in trouble when he slipped inside the opening 30 seconds, but he was able to continue and saw the game’s first shot blocked by Fran Garcia following great work from Bryan Zaragoza.
Los Blancos eventually created their first opportunity from a corner, with both Eder Militao and Jude Bellingham rising for a header that was saved by Ionut Radu. There was further disappointment for Militao, who was forced off injured having made a vital challenge to deny Duran.
Celta continued to compete well and made it difficult for Los Blancos to break them down. That made Bellingham and Antonio Rudiger resort to speculative efforts that came to nothing, before Arda Guler hit his own shot from range that at least worked Radu.
Guler was then afforded a rare major opportunity after good work from Vinicius Junior and Kylian Mbappe ensured the ball found him, but the Turkey international slid his shot wide.
Duran was then released but denied again at the other end, before Vinicius saw his instinctive attempt saved after finally getting behind the visitors’ backline.
Radu was called into action once more within a minute of the restart when Federico Valverde unleashed a venomous strike, but it was Celta who opened the scoring in the 54th minute.
After Zaragoza had been isolated, the visitors tentatively joined him in attack and enabled the winger to play the ball to Swedberg, who scored with a sumptuous flick having only come on at half-time to replace Duran.
Things then got even worse for the hosts shortly after the hour mark when Garcia received two bookings in quick succession for needless fouls. That added fire to Los Blancos’ play, but Vinicius had a shot blocked and curled another marginally wide.
The hosts kept coming, and Mbappe’s delicate attempt went tantalisingly close but landed on the roof of the net prior to Aurelien Tchouameni and Gonzalo Garcia missing with unsuccessful headers.
Ultimately, Celta stood firm, adding a late second as Swedberg rounded Courtois, earning their fourth consecutive away LaLiga win, while also ending Real Madrid’s eight-game unbeaten run in the league.
This result leaves Los Blancos - who also saw Alvaro Carreras dismissed late on - four points behind Barcelona at the table’s summit, while they have now won just two of their past seven games in all competitions as the pressure increases on Xabi Alonso.
Flashscore Man of the Match: Williot Swedberg (Celta Vigo)
