China's Zhang Shuai beat Swan 7-6 (9-7) 4-6 6-4 but was unhappy after a line judge called a baseline shot out when it appeared to hit the line.

The world number 52 suggested Swan knew the shot was out but stayed quiet and referred to the Briton's "integrity".

"I don't think it's fair to blame me," Swan, 20, replied on Twitter.

"It was the line judge's call and in the moment I didn't see it, I was just playing tennis.

"There were many bad calls for both players. This has nothing to do with my integrity."

Former Australian Open quarter-finalist Zhang replied again: "Girl, I was asking you right after they call and you 100% sure said the same."

Swan's coach Diego Veronelli also weighed in on the argument, saying it was "poor" from 30-year-old Zhang.

"I didn't see that integrity your [sic] standing for when the mistakes were in your favor," he said.

"I didn't see those great values when you've been around long enough to know you don't get the other player involved. You won the match, and yet treat your opponent as a cheater. Poor from you."