But Xavier Malisse was unable to build on Clijsters's fine work, falling 7-6 3-6 6-3 to Spain's Tommy Robredo in the second match of the Group A encounter.
The mixed doubles will decide the outcome of the tie later on day two of the ITF mixed team event.
Any thoughts that Clijsters might be resting on her laurels following her spectacular WTA Championships success last month were banished in 13 razor-sharp games at the Burswood Dome.
The blonde baseliner, cheered on by boyfriend and Australian world number one Lleyton Hewitt, pummelled Ruano Pascual - a late replacement for the recently-retired Arantxa Sanchez Vicario - with pounding groundstrokes throughout.
Clijsters capped her 2002 season with back-to-back victories over the Williams sisters Venus and Serena to win the women's season-ending championships in Los Angeles in November.
MAGIC FORMULA
But instead of revelling in that success, the 19-year-old fourth-ranked player has been working out harder than ever.
"I've been in Australia already for a month and I'm feeling very fit at the moment," she smiled after her workout against her 65th-ranked opponent.
"After winning LA this year I really wanted to work hard again to get fitter and to get stronger."
Clijsters said she hopes she now has the magic formula to beat the powerful Williams sisters - ranked one and two in the world - and she will get another chance to beat Serena on Friday when the pair clash in the final Group A match.
"I definitely don't feel any pressure there," Clijsters said. "I think it is more like a motivation for me.
"I hope that I can get other players to work harder and to get fitter, knowing that they (the sisters) are beatable. I am looking forward to Friday's match very much."
Williams, who flew into the Western Australian city on Sunday afternoon, opens her 2003 season later on Monday when she faces Uzbek Iroda Tulyaganova in the top-seeded United States' first match.
James Blake plays Oleg Ogorodov in the men's singles before the pair team up for the mixed.
