The Ring has learned that IBF heavyweight champion Daniel Dubois is feeling sick and is currently being evaluated by a doctor.

Dubois is scheduled to defend his world title against former champion Joseph Parker on Saturday night in Riyadh, Saudi Arabia.

A replacement is currently being pursued in the event that Dubois is unable to move forward with the upcoming fight.

A source has advised The Ring of the rumored three options being considered.

Those options include former world champion Lawrence Okolie, contender David Adeleye and undefeated Mourad Aliev.

Both Okolie and Adeleye are scheduled to see action in separate fights on April 25 in Manchester. Okolie has a grudge match with Richard Riakporhe, while Adeleye is set to face Jeamie TKV.

Aliev won a silver medal at the 2019 European Games. While representing France at the 2020 Summer Olympics, Aliev was disqualified from his quarterfinal bout for headbutting eventual silver medal winner Frazer Clarke.

Dubois is coming off the biggest win of his career - a five round destruction of former two-time world champion Anthony Joshua from back in September. The showcase win had a crowd of over 90,000 fans at Wembley Stadium in London.

The huge Riyadh Season card is headlined by the undisputed light heavyweight rematch between Artur Beterbiev and Dmitry Bivol.

Earlier this week, the card was modified when lightweight contender Floyd Schofield fell ill and was pulled from his scheduled world title fight with WBC world champion Shakur Stevenson. The British Boxing Board of Control would not allow Schofield to move forward with the fight.

A late replacement, undefeated Josh Padley, was eventually finalized for Stevenson.

Other fights on the card include Israil Madrimov challenging Vergil Ortiz Jr for the WBC Interim-world super welterweight belt. Callum Smith battles British rival Joshua Buatsi for the WBO interim-world light heavyweight crown. Carlos Adames' WBC world middleweight championship is at stake against undefeated Hamzah Sheeraz. And Zhilei Zhang faces Agit Kabayel for the WBC interim-world heavyweight title.