Amine Gouiri's deflected effort put Marseille ahead early at the Velodrome and 18-year-old Nwaneri soon doubled the lead.

The England under-21 international gathered the ball just inside his own half and advanced unchallenged towards the edge of the Lens box, shifting inside on to his left foot and sweeping home from 20 metres.

Gouiri netted again on 75 minutes to all but seal victory, tapping in a cross from Timothy Weah, before Lens grabbed a consolation through substitute Rayan Fofana.

Nwaneri joined Marseille on Friday until the end of the season after struggling for minutes for the Premier League leaders this term following a breakthrough 2024-25 campaign, in which he scored nine times and earned a new five-year deal with the Gunners.

Roberto De Zerbi left out the league's top scorer Mason Greenwood for the visit of Lens, in a bid to keep him fresh for Wednesday's vital Champions League trip to Club Brugge.

Instead he thrust Nwaneri straight into the team along with fellow new signing Quinten Timber, the twin brother of Arsenal defender Jurrien, against a side who had won eight in a row and 11 of their past 12 games to mount an unexpected title challenge alongside Paris Saint-Germain.

Lens had managed to maintain their one-point lead in recent weeks but reigning French and European champions PSG climbed above them on Friday after a 1-0 win at Auxerre.

Monaco's problems showed few signs of abating as they drew 0-0 at Le Havre to leave the principality club with just one victory in nine outings, dropping them down into 10th place.

Lorient extended their unbeaten run in the league to eight games with a 2-0 win at Rennes, who passed up the opportunity to move into Champions League places.