Maligned Australian Bernard Tomic has cited food poising as one of the reasons for his withdrawal during the Sydney International quarter-finals amid scathing criticism on Friday.

With the Australian Open on the horizon, a clearly disinterested Tomic sparked controversy when he retired against Russian Teymuraz Gabashvili, who was leading 6-3 3-0 after the last-eight encounter was postponed due to rain 24 hours earlier.

Tomic pulled out after a clearly audible exchange with the umpire during the first set, where he could be heard admitting his mind was on the Australian Open, which gets underway in Melbourne on Monday.

The 23-year-old was criticised by Channel Seven commenters but Tomic attempted to clarify his actions post-match.

"I'm sure you all want to know [why I retired]. I was just feeling a little bit sick last night and it was very difficult to play two matches today. So unfortunately I did the right decision, being sick, to not play today," Tomic told reporters.

"[I've] been eating the same thing at the hotel. A lot of fish and rice this week. I didn't sleep a lot last night, a few hours. We were all here at like 8am. With the traffic, everything was complicated this morning.

"When I was warming up I saw my phone, I got the text of the draw and it was very good for me. Feeling sick, playing two matches today, it was going to be very difficult.

"For me the best idea was not to play. I love Sydney so much, it was a shame I couldn't be 100 per cent today."

Tomic, who reached the fourth round at the Australian Open last year, heads to Melbourne Park to play Uzbekistan's Denis Istomin in the first round next week.

"We played four times, I think I’m 3-1 on him," Tomic added. "Second round is also good chance to win and third round — I think my first seed is Fabio [Fognini] if he can get there — I think I'm defending a fourth round so for me it’s a huge opportunity.

"I'm playing very, very well the past nine, 10 days. I just have to watch my health now."