Ulster road racer Ryan Farquhar was on Tuesday night still seriously ill in a Belfast hospital.
The 40-year-old motorcycling star suffered major injuries during a race at the North West 200 meeting on May 12.
He appeared to be improving after a spell in intensive care but suffered a relapse.
Farquhar had been interviewed and photographed in his hospital bed last week and was in a positive mood.
Lancashire rider Malachi Mitchell-Thomas was fatally injured at the same race meeting and his funeral took place in Chorley yesterday.
Meanwhile, a motorcyclist who was involved in a collision with a car near Limavady on Saturday is described as “critically ill”.
Paul Butcher, who is in his 40s, was travelling on the Ballyquin Road when the incident took place.