(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 looked little like the player who won two Grand Slams this year in a 6-1, 7-5 loss to Casper Ruud at the ATP Finals

Carlos Alcaraz struggled with a stomach issue and looked far from the player who won two Grand Slams this year while losing to Casper Ruud 6-1, 7-5 at the ATP Finals on Monday.

An off-colour Carlos Alcaraz suffered a shock 6-1 7-5 defeat against Norway's Casper Ruud in his opening match at the ATP Finals as the Spaniard's hopes of winning the year-end title for the first time suffered a blow on Monday.

Join Yara El-Shaboury for updates as Carlos Alcaraz and Casper Ruud open this year’s John Newcombe Group at the ATP Finals in Turin