PARIS, Aug 31 (Reuters) - Joey Barton is ready to joinOlympique Marseille on loan but is still waiting for StephaneMbia to reach an agreement with Queens Park Rangers before hecan sign, the Ligue 1 club's sports director said on Friday. Barton passed a medical in Marseille after arriving onWednesday and took part of a light training session on Fridaymorning. But the 29-year-old midfielder will only join the Frenchside if Cameroon defender Mbia, who has flown to London,completes his move to the Premier League. "The two clubs have reached an agreement. Mbia still has tofind one with QPR. ... More...