Watson beaten by Liu in first round of Charleston Open

Heather Watson was beaten in straight sets by Claire Liu in the first round of the Credit One Charleston Open.

The Briton lost 6-4 6-2 to the 21-year-old American.

Despite getting more of her first serves in, Watson was unable to capitalise, winning just half of the points on the first serve.

Liu also dominated on the returns, and converted four out of seven break-points in the first meeting between the two players.

Also in Charleston, Petra Kvitova retired in the second set, having lost the first against Magdalena Frech.

Frech had taken a close first set 7-6 (6) and was leading 3-2 in the second when the Czech player retired.

Elsewhere in the first round, Ukraine's Anhelina Kalinina beat Belarussian Aliaksandra Sasnovich 6-4 6-4 on Althea Gibson Court.

Sasnovich, who was only able to save one of six break points against Kalinina, was unable to play under her country's flag for the match.

Under the Association of Tennis Professionals (ATP) and Women's Tennis Association (WTA) tour policy following Russia's invasion of Ukraine, athletes from Russia and Belarus may compete in tournaments, but not under their respective countries' flags.

"At this time, players from Russia and Belarus will continue to be allowed to compete in international tennis events on Tour and at the Grand Slams," read a joint statement from the International Tennis Federation (ITF), ATP and the WTA last month.

"However, they will not compete under the name or flag of Russia or Belarus until further notice."