World No.18 Ashleigh Barty has made light work of unseeded American Sofia Kenin to advance to the second round of the Charleston Open 6-3 6-2.

There was no such luck for Samantha Stosur, who suffered yet another early exit against world No.107 Kristie Ahn.

The ninth-seeded Australian opened her clay campaign in style, breaking her teenage opponent for a 3-1 lead in the first set before taking it 6-3.

Barty immediately broke Kenin again in the second, racing to a 2-0 lead in scarcely as many minutes.

She survived two break points to extend the margin to 3-1 but there was little further resistance from the Moscow-born 19-year-old.

“I think it was always going to be a little bit of rust wearing off … I haven’t been on a clay court since the French Open last year so it’s minimal preparation for me but I’m very happy with how I served and how I played today,” Barty said.

The Australian, who teamed up with CoCo Vandeweghe to win the Miami Open doubles crown, has her sights set on a big year after a breakout 2017 which saw her enter the world’s top 20 having started in the 200s.

“We did a lot of hard work last year and the year before setting down a foundation and I feel like I haven’t got too many flaws now,” Barty said.

“We’re always wanting to get better, I’m very much a perfectionist.”

Stosur had 26 unforced errors in her 6-2 6-4 loss to Ahn. The 2010 winner surrendered the first set after a tight opening period but fought back after trailing 4-0 in the second.

Britain’s Heather Watson suffered a seventh consecutive defeat when she was beaten 6-3 6-4 by Taylor Townsend of the US.