PARIS, Aug 14 (Reuters) - Seven-times French champions Olympique Lyon have defensive worries before Sunday's Ligue 1 game at Lorient. Lyon began their title defence with a 3-0 demolition of Toulouse last weekend, Karim Benzema, last season's top scorer with 20 goals, scoring twice. However France defender Francois Clerc faces up to six months on the sidelines with a knee injury sustained against Toulouse. His replacement at right back, Anthony Reveillere, resumed training only on Wednesday after twisting an ankle. New signing John Mensah is also likely to miss the game. The Ghanian centre back is not fully fit with a sore calf. Lyon lost 2-1 at Lorient in the early stages of last season and new coach Claude Puel has warned his players they still had a lot of work to do. 'There is room for improvement and we are still building our game,' he told reporters. Their main rivals for the title finished their first league games with mixed feelings. Girondins Bordeaux, who face Paris St Germain at Parc des Princes on Saturday, were relieved to overcome Caen 2-1 at home after trailing the Normandy side before the interval. Coach Laurent Blanc urged his players to hold their nerve after being tipped as title contenders. Last season's runners-up will miss injured Marouane Chamakh for the Paris game. The Morocco striker should be replaced by Argentine Fernando Cavenaghi. Paris St Germain fear a defeat that would plunge them into a new crisis after they avoided relegation in the last minutes of last season in May. The Parisians hope experienced new signings Claude Makelele and Ludovic Giuly will be in better shape than during their opening 1-0 defeat at Monaco. Olympique Marseille, who beat Brann Bergen 1-0 in the Champions League third qualifying round in midweek, host Auxerre on Sunday after a 4-4 draw at Stade Rennes last week. 'Olympique Marseille can do something great this season as long as we do not repeat the same mistakes,' angry coach Eric Gerets said on the club's website (www.om.net).