Mark Cavendish’s Tour de France suffered another disappointment after the Manxman was outsprinted in a photo finish by Germany’s Marcel Kittel on stage 12 in Tours.The Omega Pharma - Quick-Step rider was given a perfect lead-out and appeared on course for victory, but then Kittel (Argos-Shimano) emerged from his slipstream in the final 100m and powered past to take his third win of the race by half a wheel.Both men had avoided a late crash that wiped out half of Andre Greipel’s Lotto-Belisol team and effectively ended the German’s challenge.Peter Sagan (Cannondale) claimed third to extend his lead at the top of the points classification, while Chris Froome (Team Sky) retained the race leader’s yellow jersey by diligently staying at the head of the race and finishing 14th.                             AgenciesOut-poweredCavendish’s defeat is the latest blow of a Tour in which little gone right for the Briton. Aside from victory on stage five, crashes ended his bid to win the yellow jersey on the opening day and hampered his chances in two other sprints.This time, however, he was simply out-powered by Kittel, who took the maillot jaune on stage one and has gone on to establish himself as the outstanding sprinter of the race so far.They were both ideally placed coming off the final, 90-degree right-hand corner with just over 400m to go, but Cavendish’s team-mate Gert Steegmans soon moved his team leader into pole position with a fearsome turn of speed.Kittel instantly saw the danger and jumped on to Cavendish’s wheel, and although the 24-time Tour stage-winner opened up what looked like a decisive gap after launching his sprint, the German still had strength in reserve.Late chaosHe swiftly came around his rival, pulled level and then snatched victory by a narrow margin.Behind them, riders crossed the line in small groups after the crash, which saw the Lotto-Beilsol train obliterated and Team Sky’s Edvald Boasson Hagen abandon the race after breaking his shoulder blade.Froome was unaffected, though, having ordered hisTeam Sky colleagues to the front of the peloton in the closing stages and been in front of the accident when it happened.All of his rivals for overall victory, including Alejandro Valverde and Alberto Contador, had done likewise and also finished at the head of the race to retain the status quo in the general classification.With Greipel finishing only 33rd on the stage, Sagan now leads Cavendish in the points classification by 94 points.