Relations between the Australian and Argentine Davis Cup teams sank to a new low when dozens of Australian fans arrived at Saturday's quarter-final wearing T-shirts depicting the South Americans as drug cheats.

Some 70 supporters, all members of the Fanatics club, arrived dressed in bright yellow tops bearing a cartoon showing Argentine tennis players at a needle exchange under the provocative slogan "Where's Willie?"

The Fanatics' official website said the cartoon was a direct reference to Argentina's top-ranked player Guillermo Canas, who pulled out of the tie because of a doping investigation.

Although the Fanatics are not officially recognised or endorsed by Tennis Australia, the group claim to have loose links with the sport's national body.

A Tennis Australia spokesman said offibials often reserved blocks of seats for them at Davis Cup ties while Australia's top player Lleyton Hewitt [Images] is a close friend of the Fanatics' leader Warren Livingston and has given them free tickets in the past.

However, Tennis Australia president Geoff Pollard released a statement saying his organisation had nothing to do with the Fanatics although he had discussed the T-shirts with Livingston.

"Tennis Australia does not see in advance, or have approval over, what the Fanatics provide to those who independently buy tickets through them," Pollard said.

"On this occasion, having just seen the cartoon on the T-shirts they have provided for their cheer squad I believe the intended humour falls flat (and) I have relayed my feelings."

Australia's non-playing captain John Fitzgerald refused to answer questions from journalists when asked whether he thought his team's unofficial cheer squad had acted inappropriately.

"I think that would be very wrong for me to comment on," he told a news conference.

"Who funds the Fanatics? You'd have to ask them, they go to many different sports events."

ATP INVESTIGATION

Argentina's David Nalbandian said he was not offended by the shirts but was quick to defend the reputation of his compatriot Canas.

"I don't know nothing about it but I know Guillermo and I'm sure that he didn't do nothing," Nalbandian said.

Canas told Argentine media last month that he was being investigated by the ATP over a positive doping test. He said he was innocent.

The provocative T-shirts were the latest in a series of incidents that have soured relations between the two teams during the tie.

Hewitt and Guillermo Coria began trading insults and accusing each other of bad sportsmanship after their ill-tempered singles match on Friday, won by Hewitt.

Coria accused Hewitt of swearing at him and said he wanted to kill the Australian. Hewitt responded by accusing Coria of making a crude gesture at him, spitting at the umpire and trying to shoulder charge him at the change of ends.

Fitzgerald was quick to play down the incidents, insisting there was no lingering bad blood between the teams.

"I think this has been a great tie so far, I think the players from both countries have competed as hard as they can and they've been passionate about playing for their own country," he said.

"Both teams respect the opposition and how tough they are on the court and it's all good stuff."

Argentina were leading the tie 2-1 after winning the doubles on Saturday.

• Complete tennis coverage
• All you want to know about Sania Mirza