After a catastrophic start to the Tour de France, Australian Richie Porte is on the rampage and a strong performance in the time trial is further strengthening his podium credentials.Porte, who was Chris Froome's lieutenant at Team Sky until moving to BMC during the close season, lost 1 minute 45 seconds in the second stage after suffering a puncture in the finale and was offered no support from his teammates."It's hard not to think about the second stage and the time we threw away," said Porte after taking fourth place in Thursday's 18th stage, 33 seconds behind leader Froome but gaining time on the podium contenders.Porte is now sixth overall, five minutes off the pace but only 1:08 behind second-placed Bauke Mollema, of the Netherlands, and 44 seconds behind third-placed Briton Adam Yates."It's a big goal to get on to that podium," said Porte, whose best result in a grand tour is seventh in the 2010 Giro d'Italia.Porte was the best of the big guns in Wednesday's gruelling mountain stage, dropping all the favourites but Froome with an attack inside the last two kilometres.His performance on Thursday also suggested that he is one of the freshest riders, which is crucial in the third week, when fatigue can be devastating."It was a good day but there are two more days of climbing, so I'll be trying to gain some more time," he said.Froome believes he can.  
"In my opinion he looks like the one with the most to gain in the next two stages," said the leader. "He had some bad luck. It's a shame he lost that time early on, but I believe that if he continues the way he is, he'll see himself on the podium in Paris."Froome put the hammer down in his bid to retain the Tour title with victory in the 17-kilometre mountain time trial, extending his lead to almost four minutes. The Team Sky rider is aiming to become the first to retain the title since Miguel Indurain in 1995.