Ronnie O’Sullivan says he has “struggled” in the “bubble” surrounding the Championship League tournament, which is being played behind closed doors and in a closed environment.
O’Sullivan, 44, returned to action sporting a new moustache and won his first match 3-0 in 40 minutes.
“If every tournament was to be like this then I am not sure I would be able to do it,” said O’Sullivan.
Snooker was the first sport to return to live action on free-to-air TV.
It followed the government’s ‘phase three’ coronavirus pandemic guidance, which paved the way for competition to make a comeback from Monday.
The non-ranking event is taking place without fans at the Marshall Arena in Milton Keynes, which has an on-site hotel, allowing players and staff to be contained on the complex without having to leave.
However, all personnel have had to have strict Covid-19 testing a day before they are scheduled to feature and are made to isolate in their rooms – world champion Judd Trump said he had wait 18 hours before the result of his test was known and O’Sullivan even longer.
Although a catering service is provided, O’Sullivan – who last played competitively at the Shootout in February – only entered the event if he was allowed to bring his own food as he does not “trust people” cooking for him.
But being in his room for such a long period meant he had “run out of food” and so was left “eating cornflakes for the rest of the day”.
World number six O’Sullivan added: “I have struggled. I was in the room for 24 hours so I have had a bit of a headache and started to get a bit of a cough and can’t even get the window open.
“You want to be in good health at the moment so this bubble is not ideal. If the facilities do [improve] and if you have to stay on site at the hotel and [are able to] use the gym, then it would be better.
“At the moment there is none of that so it is tough. I like my own company but it is tough being cooped up. It is not easy for me, I must admit.
“It is just about having the freedom to go out for a walk, get a bit of fresh air and a coffee.”
Much of the talk on social media was not about O’Sullivan’s century break in the first frame of his opening match against Welshman Kishan Hirani, but the addition of a handlebar moustache.
Asked how it came about, O’Sullivan said: “I set myself a challenge. As soon as we were in lockdown I was going to grow a beard but that got itchy so my partner said, ‘why not grow a moustache?’ It was a bit of a giggle really.
“A few people have said I look like a Mexican drug lord, like ‘El Chapo’. Someone even said Freddie Mercury.”
Meanwhile, the rescheduled Tour Championship – originally due to take place in March in Llandudno – will take place at the Marshall Arena from 20-26 June.