Ronnie O’Sullivan breezed past Marco Fu 6-0 in his opening match at this year’s Masters to book his place in the quarter-finals.
However, despite being in imperious form the Rocket has admitted he was not feeling 100 per cent while at the table.
The defending champion admitted after the match he had been suffering from bouts of dizziness for a number of days.
And the 42-year-old revealed he had been told by his nutritionist that it could be being caused by a lack of magnesium in his diet.
“To be honest with you, I was really struggling. I don’t know if I have got a virus or something and I just feel very dizzy,” he told BBC 2.
“I was just playing off instinct.
“I was thinking, ‘Don’t stop, just pot balls’. I was really quite struggling and have been like that for the last five or six days.
“I don’t feel ill, I just feel dizzy. I think it is maybe a lack of magnesium or something – that is what my nutritionist told me.
“I have been eating well for the last four months, maybe I have overdone the exercise when I have been at home and made myself a bit ill.”
However, O’Sullivan admitted he will not be deterred as he looks to defend his Masters title and fully expects to go deep into the tournament.
“I know I can get through it,” he added.
“I still feel good physically and you just have to do a job.”