Monaco beat Lyon 3-2 in a game marked by a series of dubious calls from the referee who later conceded all Monaco's goals resulted from off-side situations.
This contentious win at Lyon's Stade Gerland lifted Claudio Ranieri's side to within five points of Ligue 1 leaders Paris Saint Germain, who take on Saint Etienne in Sunday's late game.
For Lyon this result ended a five-match unbeaten run in the league and the former multiple French champions remain in fifth place.
Lyon, for the third match in a row, conceded a goal in the opening 10 minutes, this time Valere Garmain inflicting the damage after four minutes.
This was the first of referee Freddy Fautrel's mistakes as Garmain was set up by Dimitar Berbatov's back pass, with the Bulgarian striker clearly offside.
James Rodriguez doubled up for Monaco who once again was sent on his way by Berbatov in an off-side position after a cross from the right from Mounir Obbadi.
A dozen minutes after the restart Berbatov, clearly offside when he picked up a cross, scored from close range.
Lyon had pulled one back after the half hour when Miguel Lopes on the right flank found Jimmy Briand, who gave Lyon hope of salvaging a point with 12 minutes left on the clock with his second.
Fautrel held his hands up to a bad day at the office, declaring: "We (he and his assistants) recognise mistakes were made by the refereeing team - three goals were off-side.
"I've got other bad memories of course but tonight is a very bad memory for me and my colleagues."
Lyon coach Remi Garde said: "I'm disappointed that the players weren't rewarded for their enthusiasm and solidarity and courage.
"I'm not going to talk about the referee as I'd risk being banned."
Ranieri commented: "As for the refereeing I think it was very hard today for us and for Lyon. But when a team scores three goals away from home it deserves to win."
Earlier Montpellier held Bordeaux to a 1-1 draw.
Having sealed their place in the quarter-finals of the Champions League in midweek, Paris Saint-Germain will hope to get the better of bogey team Saint-Etienne in Sunday's late action.
On Saturday Lille let slip a chance to cement their claims on Champions League football next season when held to a goalless draw at home by Nantes.
And on Friday Reims and Marseille drew 1-1 in a result that did neither side's European qualification aspirations any good.