Portugal's Rui Costa claimed his second win of the 100th Tour de France yesterday as yellow jersey holder Chris Froome took another step towards overall victory in Paris. Movistar rider Costa shot out of a chasing peloton on the fifth and final climb to catch stage leader Pierre Rolland (Europcar) and went on to cross the finish line 47seconds ahead of German veteran Andreas Kloden (RadioShack). "A lot of Portuguese fans have supported me through this Tour and I want to thank them," Costa said after the 19th stage. Team Sky leader Froome came over the finish line just under nine minutes in arrears but with his 5 minute, 11 second overall lead over Spanish rival Albeto Contador intact. On the penltimate day of climbing on the race, Contador's Saxo team tried several times to test Team Sky and Froome by upping the pace on the last two of the stage's five climbs. But while their efforts helped drop several of Froome's teammates, the Kenyan-born Briton finished on the wheel of Australian teammate Richie Porte, who had been briefly left trailing on the final climb. Ahead of today's final day in the Alps, the 125 km 19th stage from Annecy to the summit of Annecy-Semnoz, Froome looks virtually assured of succeeding compatriot and teammate Bradley Wiggins as the race champion. Contador's biggest worry may now be protecting his runner's up place from Colombian climbing specialist Nairo Quintana, who is third overall at 5:32. Meanwhile, Australian Richie Porte's racing skills appear to know no bounds on the Tour de France, and included breaking the rules on an epic 18th stage to the Alpe d'Huez. Team Sky rider Porte has been demonstrating his faith towards yellow jersey holder Froome throughout the race, but on the 172.5 kilometre trek from Gap to the summit it had to go beyond the normal call of duty. Froome, who began the day with a 4 minute, 34 second lead on second-placed Spaniard Alberto Contador, felt the first signs of hypoglycemia early on the second climb of the 13.8 kilometre ascent to the legendary summit. By the time he was approaching the 5 kilometre to go mark, the Kenyan-born Briton's arm was in the sky desperately asking for assistance. With no feeding allowed in the final 29 kilometres, Froome was in trouble - but Porte, whose job is to set a pace for Froome that is not too hard but which can do damage to rivals, was on hand. The Tasmanian dropped back to the Team Sky car, collected a handful of sugar-rich power gels and rode back up the road to feed his team leader. Froome and Porte were both sanctioned with a 20 second penalty but in the grand scheme of things it was irrelevant. "I was really going into a little bit of a sugar low then," explained Froome. "I asked Richie to go back to the car … he just gave me some gels to get me to the finish. "I don't know if it helped me with 5 kilometres to go but it was really good to have Richie there, he did a fantastic job."