Mark Philippoussis' cousin David suffered a heart attack during the player's round one Australian Open clash and remained unconscious.

Paramedics immediately attended to Philippoussis' cousin, who was rushed to Royal Melbourne Hospital where he was listed as being in a serious but stable condition.

Philippoussis' father Nick left the court during the first set to check on David, with the player aware something was amiss but not finding out what happened until after the match.

"My cousin had a heart attack in the toilets and fortunately there was a doctor with him," said Philippoussis after defeating Sweden's Thomas Johansson 7-6 (8-6) 6-2 7-6 (7-4) to set up a second round meeting with Frenchman Fabrice Santoro on Thursday.

"I saw my sister was not there, I didn't know what was going on, I wanted to concentrate on the match. I was told as soon as I got off the court."

A quietly-spoken Philippoussis was not prepared to divulge his cousin's surname.

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