Justine Henin made a successful return after six months out through injury at the Hopman Cup on Saturday but ended up a loser as Belgium were beaten 2-1 by hosts Australia in the opening match of the mixed team event.
The former world number one, who suffered a partial ligament fracture to her right elbow at Wimbledon last year, made more unforced errors than usual but was still too good for Alicia Molik as she won 6-4 6-4 to put Belgium ahead.
Another former world number one Lleyton Hewitt levelled the tie after a 6-4 6-3 win over world number 178 Ruben Bemelmans and the Australians then joined forces to win the deciding mixed doubles 1-6 6-3 7-6.
Top seeds Serbia, represented by Novak Djokovic and Ana Ivanovic, begin their campaign on Sunday while British number two seeds Andy Murray and Laura Robson open their title bid on Monday.
Temperatures outside the Dome were pushing the 40 degree Celsius mark and it was almost as warm inside as players and the 7,000-strong crowd soon got involved in a topsy-turvy tussle.
Henin, who came back to the tour at the beginning of 2010 after a retirement that lasted 20 months, began well against world number 129 Molik but was understandably rusty as she allowed Molik back from 3-0 down to level at 4-4 in the second.
But when she needed to, Henin responded and she broke serve again in the ninth game and served out for the match.
"Alicia's not the easiest opponent because she changes the rhythm a lot and I lost a bit of my rhythm, but it was good to win," said Henin, who intends to spend her day off on Sunday at the beach.
"I can't play at 100 percent yet, without pain, but the elbow is getting better. A few months ago I didn't know if I was going to be able to come to Australia.
"I'll need a bit of time probably, to be at my best, but my motivation is high. I just have to be patient."
Belgium then looked on course for victory in the mixed doubles when they led the deciding match tiebreak 8-6 but Australia roared back to take it 10-8.