The safety of Tour de France riders is paramount when it comes to interactions with fans.

But during yesterday's Alpe D'Huez stage high in the French mountains, one fan tried to chase down American cyclist Tejay Van Garderen.

But before the fan could get his hands on his quarry, an unidentified man in a blue shirt left him flat on his face by tripping him up as Van Garderen pedalled up the mountain.

The fan became irate and looked like he wanted to have a go at the man who tripped him up...