The bizarre incident happened as Katusha-Alpecin rider Haller rode along after the stage finish with a bottle gripped between his teeth.
The fan inexplicably puts his arm out and tries to pull the bidon from the Austrian’s mouth.
Haller stops his bike and confronts the fan, using some bad language and asking “what is wrong with you?”
The fan apologises and puts hands in the air, as a finish line steward runs in to separate the pair. Haller then rides away while still criticising the fan.
It was a pretty stupid thing for the fan to do; not least because the riders will often give away their bottles to fans if they are asked.
But taking one literally from the mouth of a cyclist on an exhausting Grand Tour is not the way to go.
It is possible, however, that the fan simply got carried away in the moment and in the general excitement of the Giro.