Briton Anthony Joshua, who reclaimed his world heavyweight titles with a clinical victory over Andy Ruiz Jr on Sunday, says a health issue had left him tired and drained before his shock defeat to the Mexican-American in their first fight in June. Joshua regained the IBF, WBA, WBO and IBO titles with a unanimous points victory in Saudi Arabia, six months after he was sensationally dethroned by Ruiz at Madison Square Gardens in one of boxing’s biggest upsets. “I had some issue with my health which I was going through for a long time,” said Joshua after judges scored the ‘Clash on the Dunes’ 118-110, 118-110 and 119-109 on Sunday. “I didn’t know what was wrong with me. I felt so tired and drained and thought it must be down to training. “In the changing room before the fight (in New York) I got a bucket of ice and was putting my head in it thinking ‘why do I feel so tired?’ “Even in this camp I had an operation done but as I’d started training in June I had no issues.” Joshua did not elaborate on the nature of the operation. For the first title defence of his second stint as world champion the 30-year-old is likely to face either unbeaten Ukrainian Oleksandr Usyk, the WBO’s mandatory challenger, or Bulgarian Kubrat Pulev — the mandatory challenger for the IBF.