The relationship between Tomic and Rafter is already fractured, but Tomic's decision to pull out of the April tie has riled the former US Open champion.

Tomic, 20, who moved to the quarter-finals of the Sydney International with a straight-sets win over Florian Mayer on Wednesday, was dumped by Rafter last month for Australia's first tie against Taiwan in February so he could work on his game.

Tomic admitted he wouldn't be playing in the second tie of the Davis Cup when he was in Perth last week and again in Sydney this week, but it wasn't until Lleyton Hewitt revealed his disappointment with the decision on Wednesday that it became clear Tomic had again fallen out with Rafter.

Tomic has spoken to Rafter since he was dumped but doesn't expect to make contact again for another eight months.

''I spoke to him and I was very clear,'' Tomic said of his conversation with Rafter. ''I don't think we'll be in contact until September. From there, we'll see. That's all I can say.''

His comments came just hours after Hewitt, who won his first round match at the Kooyong Classic on Wednesday, revealed Rafter was angry with Tomic's decision. Hewitt said he was eager to hear Tomic's side of the story.

''I haven't spoken to [Bernard] about it but I would like to have a chat at some stage about it and just [find out why],'' Hewitt said. ''I know Pat is pretty frustrated but he wants to have the best possible team he can have, and Bernie is in that.

''It is disappointing he is not playing the first tie but that is for other reasons than Bernie missing it himself. But there is still a bit of time before the second one, so we will have to wait and see. Obviously he has to work on a few things before he gets back into the team, and whether that has had any influence on him missing the second one, I don't know.''

While the Tomic-Hewitt relationship began on shaky grounds after Tomic rejected the veteran's offer of practice sessions at Wimbledon in 2009, which Tomic later said was because of a swine flu scare, Hewitt said the pair had turned things around.

''I feel like the last … two years, I have gotten on probably the closest out of everyone with him, which a lot of people would find amazing after a few years ago,'' Hewitt said.

While Rafter is disappointed with Tomic, he would be pleased to see he has turned his game around and is producing the type of tennis Australia expects from him.

He has set up a quarter-final clash in the Sydney tournament with defending champion Jarkko Nieminen after a 7-6 (7-4), 6-2 win just 24 hours after his battle with fellow Australian Marinko Matosevic in 40 degree temperatures.

Despite the ordeal of playing through the searing heat on Tuesday, Tomic had a practice session after the match, a reflection of his new-found commitment.

He admitted that a year ago he wouldn't have contemplated working on his game straight after such a match.

''Every time I play now, I look at the stuff where I probably lacked on the court, and I go work on it for 10, 15 minutes after. That's the best time to do it, when you feel confident with yourself, when you've won,'' he said.

The first set went into a tie-breaker, but after racing to a 3-0 advantage, Mayer was chased down by Tomic, who won seven of the next eight points to seal the first set in a 7-4 tie-breaker triumph.

The second set and the match was all but decided in the fifth game when Tomic broke the German for the first time in the match.

It was the catalyst for an explosive finish from Tomic, who produced the most brutal and convincing service game of the contest to take a 4-2 lead and eventually the match.