(Reuters) - World number three Carlos Alcaraz is unlikely to be at his best for Wednesday's ATP Finals match against Andrey Rublev as the four-times Grand Slam champion continues to struggle with illness, the Spaniard's coach Juan Carlos Ferrero said.

Carlos Alcaraz's performance in the ATP Finals is under threat as he battles illness, affecting his preparation for a crucial match against Andrey Rublev. Coach Juan Carlos Ferrero reveals the Spaniard's struggles with breathing,

The ATP Finals’ organizers have already published the order of play for Day 6: Alcaraz and Zverev will face each other in the day session, while Ruud and Rublev will clash in the night session.