World number one Lleyton Hewitt got his season off to a cracking start yesterday, beating 13th-ranked Roger Federer 6-3 0-6 6-4 as Australia defeated defending champions Switzerland in the Hopman Cup.

Hewitt's victory gave the hosts a winning 2-0 lead in the Group B match of the mixed team event after Alicia Molik had nosed Australia in front, beating Miroslava Vavrinec 6-3 6-4.

"It's always tough, the first match of the season ... only having a couple of weeks after the Davis Cup and all that emotion, it was pretty hard to come out here and play," Hewitt said.

"I was pretty down after we lost the Davis Cup, but it has been an incredible year." Australia lost the Davis Cup final 3-2 to France earlier this month.

Hewitt and Molik beat the Swiss pair 6-3 6-1 in the mixed doubles to complete the rout.

In yesterday's other Group B clash, Spain beat Argentina 3-0. Arantxa Sanchez-Vicario beat Argentina's Paola Suarez 6-2 6-3, Tommy Robredo beat Mariano Zabaleta 4-6 6-2 6-3 and the pair teamed up to win the mixed doubles 4-6 7-5 7-6, 10 points to five in the deciding 'super tiebreak'.

Despite an up and down performance which saw him blasted off court in the second set, Hewitt thrilled a record 8,486 crowd at the Burswood Dome in Western Australia with powerful hitting from the back of the court.

The 20-year-old blew a hole in Federer's defences in the sixth game of the opening set for the decisive break.

The Swiss player missed two break points of his own while trailing 5-3, dumping a backhand in the net and sending a topspin lob centimetres long, and Hewitt sealed the set in just 29 minutes when Federer pushed a return beyond the baseline.

Federer turned the game on its head in the second set, walloping winners all over the court as Hewitt's concentration slipped.

But in the third set the 20-year-old produced the sort of form that brought him a first Grand Slam title at the US Open in September, sending Federer scurrying around the court.

Defending champions Switzerland won the mixed team event last time largely on the strength of their women's number one Martina Hingis.

But with the inexperienced Vavrinec partnering Federer this time, their crown looks decidedly unsteady.

"The first match is always a nerve-wracking one," Australia's Molik said. "She was pretty much an unknown going into that match and I just concentrated on my own game ... I'm happy with the way it went."