PARIS, Feb 23 (Reuters) - A Fred double earned Olympique Lyon a 2-0 home win over bottom club Metz as the six-times champions opened a four-point gap at the top of Ligue 1 on Saturday.

Fred, who had started only three league matches this season, opened the scoring on nine minutes after being set up by France striker Karim Benzema.

He made it two 23 minutes into the second half by chipping the ball past Metz keeper Christophe Marichez.

Lyon, who were back to their best in a 1-1 draw against Manchester United in the Champions League on Wednesday, have 52 points from 26 matches.

Second-placed Girondins Bordeaux, who host Lille on Sunday (1955 GMT), have 48 points from 25 games.

Third-placed Nancy came from behind to post a 2-1 victory against RC Lens, who had not lost in their last five league outings.

Kader Mangane put the visitors ahead just before the interval but Pascal Berenguer and Youssouf Hadji netted within five minutes midway through the second half to give the Lorraine side all three points.

Goals by Marco Basa and Anthony Le Tallec gave Le Mans a 2-1 win at Valenciennes in an ill-tempered game at Nungesser stadium and moved them up to fourth in the table on 40 points.

Le Tallec and Valenciennes defender Williams Martinez fought at halftime and were both shown a straight red card.

Troubled Paris St Germain remained four points above the danger zone after a 1-1 home draw against Monaco.

Earlier on Saturday, Geoffrey Dernis scored twice to help St Etienne pull away from the relegation zone with a 3-1 win at Caen.

On Sunday (1800 GMT), in-form Olympique Marseille travel to Toulouse.