Fabregas winner helps struggling Monaco beat Toulouse 1-0
The former Chelsea, Barcelona and Arsenal midfielder latched onto a loose ball in the penalty area following good work down the left from Gelson Martins, and thumped the ball in just under the crossbar midway through the second half.
Fabregas was signed by his former Arsenal teammate Thierry Henry, but Henry was sacked as coach last week to pave the way for Leonardo Jardim's return after he was replaced in October by Henry.
Jardim was about to make a substitution when Fabregas scored, and the Portuguese coach pumped his fists in delight. With good reason, too, since the win moved eight-time French champion and former Champions League finalist Monaco up one place into 18th and the promotion-relegation spot.
It was 2017 French champion Monaco's first home win of the season.
Mario Balotelli made his first start in attack since joining Marseille , but it made little difference as the defense crumbled again in losing at Reims 2-1.
Reims was 2-0 up when forward Clinton NJie's looping header got Marseille back into the game; but his 86th-minute goal came too late for last season's Europa League runner-up.
This latest defeat increases the pressure on Marseille coach Rudi Garcia, whose objective was to secure a Champions League place next season.
Instead, his side is in 10th place and conceding too many goals.
Amiens dropped down to 19th on goal difference after losing at Rennes 1-0. Defender Mehdi Zeffane grabbed a late winner with a clever flick inside the front post after being set up by striker M'Baye Niang's neat footwork down the left.
Unbeaten league leader Paris Saint-Germain faces one of its toughest tests of the season at Lyon, which is challenging Lille for second place and automatic qualification for next season's Champions League.
Lyon can ill afford to lose, because defeat would leave it trailing second-placed Lille by six points.