PARIS, Sept 16 (Reuters) - A first-half strike by Etienne Didot earned Stade Rennes a 1-0 victory over Lorient in the Breton derby and fourth place in Ligue 1 on Sunday. Midfielder Didot netted in the 34th minute with a powerful 30-metre free kick to give Rennes their fourth win of the season. Pierre Dreossi's side, who have not lost since their opening match, have 15 points from eight matches and now lead ninth-placed Lorient by three points. Earlier on Sunday, Paris St Germain clinched their second victory of the Ligue 1 season when they beat Monaco 2-1 at the Stade Louis II. The Parisians, who are more at ease away from their Parc des Princes home, moved up to 11th in the table with 11 points from eight games. Monaco dropped to sixth on 13 points after a second league defeat in a row. PSG went ahead six minutes from the break when defender Sylvain Armand headed home from a Jerome Rothen free kick. Rothen also set up PSG's second, sending over a cross for striker Amara Diane to beat keeper Flavio Roma with a fine header in the 53rd minute. Monaco netted a consolation goal with five minutes remaining courtesy of a 25-metre free kick by Jeremy Menez. On Saturday, Karim Benzema scored a hat-trick to help champions Olympique Lyon thrash Metz 5-1 and move up to second spot, a point behind Nancy, who were beaten 1-0 at RC Lens.