Swiatek makes hot start to summer with United Cup rout

Casper Ruud levelled the tie for Norway with a 7-5 6-3 win over Hubert Hurkacz in the men's match but nothing could take the shine of Swiatek's eye-catching comeback performance.

The five-time grand slam champion was playing her first tour match since a one-month suspension late last year after returning a positive test for the angina medication trimetazidine, which the International Tennis Integrity Agency (ITIA) accepted was caused by contamination of a medicine she was taking for jet lag.

While saying on arrival in Australia that she'd expected more negative reaction to her plight, Swiatek has come under fire from players including Novak Djokovic and Nick Kyrgios in recent days.

Kyrgios claimed the bans of Swiatek and men's world No.1 Jannik Sinner for taking prohibited substances were "disgusting" for tennis, while Djokovic agreed they were "not a good image" for the sport.

Swiatek had few worries in disposing of Malene Helgo in little more than an hour. (Mick Tsikas/AAP PHOTOS)

But if Swiatek has even heard of the remarks, she didn't seemed fazed on court in her first match of the summer.

The former world No.1 broke the world No.404 five times, won 88 per cent of points after landing her first serve and clubbed 24 winners to more than offset eight unforced errors.

No wonder Swiatek said she was happy with "everything" in her game after receiving a rousing ovation from the crowd.

"I'm happy for sure with the performance. It's not easy to play for your country sometimes - the pressure is a bit bigger," she said.

"But I'm really excited. Every year I feel like I can really take so much energy from that and also from the people, from the fans.

"I feel good. I feel happy for sure. I'm happy that I can play tennis overall."

After losing to Czechia in their opening tie, Ruud and Ulrikke Eikeri must beat Swiatek and Jan Zielinski in the deciding mixed doubles rubber to stay in the hunt for a quarter-final berth.