US national team star Folarin Balogun was among the scorers as Monaco won 3-1 away to Paris Saint-Germain in Ligue 1 on Friday, dealing a blow to the side from the French capital before they face Chelsea in a crunch Champions League last-16 tie.
Maghnes Akliouche gave Monaco a first-half lead at the Parc des Princes and Aleksandr Golovin doubled their advantage moments after coming off the bench in the second half.
Bradley Barcola pulled one back for the reigning European champions, but Balogun hit back shortly after with a fifth goal in his last five games as Monaco claimed a precious win in their quest to qualify for Europe next season.
The principality side were seeking revenge after a 5-4 aggregate defeat by PSG in the Champions League knockout phase play-offs last month, when they squandered a two-goal lead before losing 3-2 in the first leg and then came up short with a 2-2 draw in the return.
That result allowed Luis Enrique's side to reach the last 16 and they are now preparing to put their title on the line against Chelsea, with the first leg in Paris next Wednesday and the return on March 17.
That will be a season-defining tie for PSG, who won the Champions League for the first time in their history last season, before losing 3-0 to Chelsea in the final of the Club World Cup.
Defeat against Monaco is a setback in their bid to win a fifth consecutive Ligue 1 title, with closest challengers Lens now in a position to trim PSG's lead at the top from four points to one if they beat bottom side Metz on Sunday.
This was PSG's fourth league loss in 25 games this season, as many losses as in the last two seasons combined.
They have now been beaten seven times in all competitions in 2025/26, and four times since the start of the calendar year.
Luis Enrique will be concerned at how far his team appear to be from the remarkable form they showed in the second half of last season on their way to winning the Champions League, as well as a French league and cup double.
DEMBELE RETURNS
One plus here was the latest return from injury of last year's Ballon d'Or winner Ousmane Dembele, who came off the bench in the second half.
However, he has started only 14 of PSG's 40 games this season and it remains to be seen how long he will be able to play against Chelsea.
Monaco beat PSG 1-0 at home in November and were very much worthy winners here, going ahead just before the half-hour mark.
PSG's Warren Zaire-Emery gave possession away as he set off on a dribble inside his own box, and the ball ricocheted back into the path of Balogun, who teed up French international Akliouche to score.
The hosts were wasteful with their final ball, and Golovin showed them how it should be done on 55 minutes, the Russian applying a clinical first-time finish with his first touch having come on as a substitute after Vitinha inadvertently played the ball into his path.
Golovin then forced a great save from his compatriot Matfei Safonov in the PSG goal, and the home team got one back on 71 minutes.
Achraf Hakimi set up Barcola to score his 10th of the season with a first-time effort that took a deflection off Jordan Teze and beat Monaco keeper Philipp Koehn at his near post.
But Monaco snuffed out the PSG comeback, Balogun's shot from outside the area going in via a touch off Nuno Mendes.
That was the 13th of the season in all competitions for the striker who is set to play a leading role for co-hosts the United States at the World Cup.
Monaco, who also saw Simon Adingra hit the bar late on, have won five and drawn two of their last seven Ligue 1 games and are up to fifth in the table.