Rafael Nadal has pulled out of the 2018 Paris Masters, clearing a path for Novak Djokovic to become world No. 1.

Nadal, the ATP's top-ranked player, cited an abdominal problem as the reason for his withdrawal, per Stuart Ballard of the Daily Express.

The decision continues a worrying trend for the 32-year-old Spaniard:

Nadal's call also means a dramatic change in standing for Djokovic:

Nadal said medical advice prompted his decision to leave the tournament, per Ballard.

One of the undoubted favourites for the Paris Masters, Nadal was set to face Fernando Verdasco in the round of 32 on centre court. With the match cancelled, Verdasco has been left face Tunisian Malek Jaziri, where the former currently trails by a set.

Nadal isn't the only high-profile player to leave the French capital due to injury:

Both Federer and Djokovic will be among the favourites to take the title without Nadal in the mix. The decorated duo represent the strongest challenge to Jack Sock, despite the defending champion making it through to the third round after beating Richard Gasquet in straight sets on Wednesday.

It also means Nadal has missed the chance to cement his No. 1 ranking ahead of the end of the year.