Australian Open champion Sofia Kenin didn't miss a beat as she returned from a three-month layoff caused by the coronavirus pandemic with a straight-sets victory over Alison Riske at the Credit One Bank Invitational in Charleston, South Carolina.

The 21-year-old beat fellow American Riske 6-1, 6-1 to kick off the women's team event which is being held on the same green clay courts that host a WTA Tour tournament every year.

The event is one of the first to give WTA players a chance to compete as their tour preps for a return to action in Palermo, Italy, on 3 August.

Kenin had been busy before the break, playing six WTA tournaments and Fed Cup in early 2020.

She followed up her first Grand Slam triumph in Australia with a win at Lyon in France and admitted she found it difficult to accept when the Covid-19 pandemic brought the tour, along with most global sport, grinding to a halt.

"It wasn't easy," she said. "I felt like I was on a roll. I just focused on staying healthy," added Kenin, who said she was able to play "almost every day" on a private court even as lockdown rules were in place to slow the spread of the virus.

Kenin's victory gave captain Bethanie Mattek-Sands' Team Peace a 1-0 lead over captain Madison Keys' Team Kindness in the 16-player team event.

"I knew I didn't have a lot of match play (recently), so I just tried to take my time and play my aggressive game," said Kenin, who is ranked No 4 in the world.

Strict social distancing rules were in place for the event, with Kenin giving a little smile and shrug as she tapped racquets at the net with Riske after the match.

Players called their own lines, and a reduced crew of ball kids wore gloves and masks, picking up balls in tubes to avoid handling them.

A scattering of people in the stands included players and a minimal number of family members or support team members.

The event, which continues through Sunday, was to have included both of the two most recent Grand Slam winners in Kenin and 2019 US Open champion Bianca Andreescu.

But Canada's sixth-ranked Andreescu, who hasn't played a competitive match since October after suffering a left knee injury at the WTA Finals in Shenzhen, China, withdrew on Monday saying she had decided to focus on preparing for a return WTA action when that becomes possible.