Van der Poel maintained his race lead despite finishing 12th behind stage winner Mark Cavendish (Deceuninck Quick-Step) overnight but knows he could relinquish the maillot jaune once the 27.2-kilometre trek from Change to Laval comes to a close.
“It will be difficult for me, we have to be realistic about that,” the Alpecin-Fenix rider said.
“I don’t train much on it (the time trial bike) but will do everything I can to keep the jersey.”
The 26-year-old will face stiff competition from general classification contenders Wout van Aert (Jumbo-Visma), Richard Carapaz (Ineos Grenadiers) and Julian Alaphilippe (Deceuninck Quick-Step) – the latter currently eight seconds behind in the overall rankings.
Van Aert is the hot favourite to take the yellow, with three Tour stage victories already to his name and 31 seconds separating him from the top.
It’s believed the rolling roads could benefit the Belgian, while injuries to Primoz Roglic (Jumbo-Visma) and Geraint Thomas (Ineos Grenadiers) could limit the pair’s ability to gain ground.
Aside from the proven Alaphilippe, Stefan King (Groupama-FDJ) and Stefan Bissegger (EF Education-Nippo) are also ones to watch who have circled the stage since the start of the Tour.
And with young American Brandon McNulty (UAE Team Emirates) also looming as a threat, the lumpy course promises to serve up an exciting race against the clock.
The Tour de France continues tonight with Stage 5 and you can watch all the action on SBS and SBS On Demand from 8:30pm (AEST), with the SKODA Tour Tracker app commencing from 8:05pm.