Little-known Hungarian player Amarissa Toth has apologised for erasing a ball mark during her Hungarian Grand Prix match against Zhang Shuai, with the disputed line call leading to the Chinese world No. 28’s retirement from the contest in tears.

On Tuesday, second seed Zhang hit a crosscourt forehand that appeared to land on the line but was called out by the line judge. The chair umpire then stepped down to take a look at the mark and confirmed the ball had landed outside the line.

The match continued for one more point but the disagreement over the disputed call continued, before Toth walked up to the mark and used her shoes to erase it.

Zhang looked visibly distressed during the changeover and she opted to retire while trailing 5-6 in the opening set of their round-of-32 match in Budapest.

The home crowd jeered Zhang during the incident, while Toth shook hands with her before putting her arms up in celebration.

Toth’s behaviour was swiftly condemned by peers and greats like Martina Navratilova on social media, with Zhang taking to Instagram to complain about the call.

“I did not think that my first ever WTA main draw success would cause such a storm,” Toth said in a statement uploaded to the tournament’s Facebook page after her defeat to Ukraine’s Kateryna Baindl on Thursday.

“I am extremely sorry for what happened, I respect Zhang Shuai as a player and as a person... I do realise I shouldn’t have celebrated the way I celebrated after the match and I’m sorry. I was acting in the heat of the match and got caught up by my emotions and the moment...”

Toth had initially defended her decision to erase the mark.