Anthony Joshua has said he did not suffer a panic attack before his defeat to Andy Ruiz Jr., telling fans his performance was to blame and he will "have to take my loss like a man".
The former unified world heavyweight champion fell to an enormous upset at Madison Square Garden on Saturday night when the unheralded Ruiz knocked him out in the seventh round to take the WBA, WBO and IBF world titles.
The unexpected loss -- a first of Joshua's career on the night he made his U.S. debut -- caused people to speculate about his mental and physical health, but the British fighter dismissed any suggestion he was not fight-ready and said he alone was to blame for his poor performance.
"I warmed up really well. I had no panic attack -- I'm not that type of person, you know me," Joshua said in a video message to his fans. "I have to take my loss like a man; no blaming anyone, no blaming anything. I'm the one who went in there to perform and my performance didn't go to plan.
"I have to readjust, analyse, do my best to correct it and get the job done in the rematch."
Joshua had met with promoter Eddie Hearn and trainer Rob McCracken in New York before he released the video on his YouTube account, entitled "my loss from my side".
Hearn has confirmed the former champion exercised his option for a rematch against Ruiz which will likely take place towards the end of 2019.
A decision is still to be made on where the fight will take place, with the option of another Madison Square Garden bout up against a rematch at a venue in the U.K., but Joshua said he didn't mind where the fight happened.
"Congratulations to Andy Ruiz, he has six months or so to be champion because the belts go in the air and he is going to have to defend those titles against myself," Joshua said.
"Within our contract we were negotiating we added some clauses, as you do, so naturally we added a rematch clause with a date and location. I would not mind if it was in New York again or in England. New York opened their arms to me and my whole team and it was phenomenal."
Joshua was sent to the canvas four times by Ruiz before the fight was finally ended. The former champion appeared to be sluggish throughout and at the end of the sixth round asked his corner "Why am I feeling like this?"
But he confirmed there had been no problems in his pre-fight camp in Miami and he had not eaten any contaminated food.
"There have been a lot of accusations and worries about what was wrong with me," he said.
"I want to tell you this: I am a soldier and I have to take my ups and my downs, and on Saturday I took a loss."
Joshua's advisers, including McCracken, have come under fire, but the fighter defended his team, whom he said he would "remain loyal to".
"The whole training camp team pulled together and did a great job," Joshua said. "There were a lot of issues going on with this fight, with Jarrell Miller then Luis Ortiz pulling out and Ruiz stepping in.
"They've done a great job for me, not only inside the boxing ring but mainly as a human being. They really developed me as a person which is important. These guys have been with me for years.
"To my supporters as well, I'm not going to change on you and act any different or change my ways. I'm still the same old Anthony Joshua, same motivation to better myself through boxing."