A tired Bernard Tomic felt like he had just played a nine-set monster after fighting back to secure a 4-6 6-3 6-2 win over Italy's Andreas Seppi at the Hopman Cup yesterday.

But it wasn't enough to lift Australia to victory, with Italy winning the deciding mixed doubles to end the home nation's title hopes.

Tomic was feeling the effects of a heavy training load after practising for five hours on Monday and a further two hours before he took on Seppi.

The gruelling schedule took its toll on Tomic as he conceded the first set.

But the 21-year-old dug into his reserves to turn the tables, with his win levelling the tie at 1-1 after Sam Stosur had earlier crashed to a 6-4 6-4 loss to Flavia Pennetta.

Italy won the mixed doubles 6-3 6-4 to ensure Australia's title drought would extend to a 16th year.

Tomic, who lost his opening Hopman Cup match in straight sets to Canada's Milos Raonic, said his heavy training load was designed to get him in the best possible shape ahead of the Australian Open.

"This week is a training week for me. I'm playing a little bit tired, but who cares?", said Tomic, who is working under new coach Velimir Zovko.

"At the end of the day, I've got to push myself.

"I know I was feeling a bit tired out there, but it's only going to make me stronger for the big one in a few weeks."

Australia's Samantha Stosur said she was frustrated but not despondent after slumping to consecutive singles defeats.

The 2011 US Open champion, who suffered a three-sets loss to Eugenie Bouchard on Saturday, committed 26 unforced errors against Flavia Pennetta.

Stosur has famously struggled to find form during the home tennis summer in recent years, but says there's no need to panic just yet ahead of the Open.

"It's disappointing not to get a win again. But I thought I played some good tennis," Stosur said.

"Every year I've managed to play well at some point. It's not like you start not so well and then your whole year is shot. Time on court is the most important thing at the moment and that's why this tournament is so great.

"I'm still pretty happy with the way I'm hitting the ball. There's room for improvement, but I don't think it's the worst start I've ever had."

Stosur has now lost all five meetings with Pennetta, ranked 13 places behind her. AAP