Dutch cycling star Mathieu van der Poel has been forced to withdraw from the Tour de France due to a pneumonia diagnosis, his Alpecin-Decunninck team said on Tuesday.

Van der Poel joined a short coffee ride during Monday's rest day to show off a commemorative kit in honor of his grandfather Raymond Poulidor, but was already struggling with illness.

"Mathieu had been experiencing symptoms of a common cold over the past few days. Yesterday afternoon, his condition began to worsen significantly," the team said in a statement just a few hours before the start of stage 16 to Mont Ventoux.

"Medical tests revealed that Mathieu is suffering from pneumonia. In consultation with the medical staff, it was decided that he can no longer continue the race. His health is the top priority, and rest and recovery are now essential," it added.

The team said that Van der Poel will be required to rest for at least one week before undergoing further medical examinations to assess his recovery and determine the next steps in his rehabilitation.

Van der Poel won the second stage of this year's Tour de France and wore the yellow jersey for four days. Ahead of stage 16, he was 41st in the overall standings.