Michael Matthews believes the call of nature may have prevented him from claiming a second-straight Tour de France stage victory.
The Australian sprint star was in a 28-man breakaway group with less than 40 kilometres to go in Sunday's 15th stage when he succumbed to the urge to urinate.
"I really think I had the legs to win today ... I think it cost me the win," Matthews told News Corp Australia.
"When you're in the breakaway, it's hard to stop for a nature break because there's so many people on the side of the road.
"You can't do it while you're riding.
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"I was really busting the whole race and the only time I could really find to stop and have a piss was on the climb."
Matthews won the intermediate sprint to claim a maximum 20 points during the stage between Laissac-Severac l'Eglise and Le Puy-en-Velay.
But it wasn't enough to claim the lead sprinter's green jersey from Marcel Kittel, although he did cut the German's points classification lead from 99 to 79.
Failing to win the stage cost Matthews 30 points.
Chris Froome retained the overall leader's yellow jersey on Sunday, while Dutchman Bauke Mollema won the 189.5km-stage
A day earlier, Team Sunweb's Matthews burst clear for his first stage win of this year's Tour.
