Harriet Dart accuses umpire of 'embarrassing' herself in tense clash with Boulter

Dart said to the official Kelly Rask that she was "embarrassing yourself" after the British number two was convinced a ball landed out during a rally in the second set of a tight tussle and later accused Rask of "threatening" her.

Defending champion Boulter kept out of the drama and sealed a 6-7 (5) 6-4 7-5 victory.

The players are good friends off the court, but Boulter will probably leave Dart alone until she cools off.

Dart, back in the world's top 100, was unhappy with the line judging throughout but first lost her temper midway through the second set.

A ball from Boulter was called out but overruled by Rask and Dart shouted: "The ball is so far out, this is embarrassing, you're embarrassing yourself. You should be embarrassed."

After losing the replayed point she then placed the ball down on the ground and said: "It was here, no joke, everyone here knows it."

Rask replied: "Harriet, stop now or you're going to get a code (violation), I've had enough now. That's it."

At the end of the game Dart then asked to see the referee which is when she offered a wager with Rask.

Dart vented at the umpire: "I've got a reason to call the referee, because of the calling, I'd like them to watch. If we watch that back I can promise you, I would back £50,000 that ball is out, I'd shake your hand now. It's a joke how far that was out."

Two games later Dart spoke to referee Jane Harvey and accused Rask of unjustly "threatening" her with a code violation.

Dart said the level of line-calling was "pretty appalling" and has called for technology to be used across the board.

"To be threatened by someone for saying that a call was embarrassing is a bit of a joke," she said.

"It makes sense that we need to move to electronic line calling for everywhere, for everyone's sakes, there's too many disruptions, not just for me but for both of us. A few points here or there can really totally change a match."

On her altercation with Rask, Dart added: "Give me a code violation or don't, I think she was a bit embarrassed by the situation. We are all professionals here.

"I have played so many tennis matches in my career and this one was a little bit disappointing with some of the things. I think she can also reflect on that. It is really challenging.

"When there are a few calls that go against you and they are tight you then have to alter how you play because you are afraid the ball is going to be called out.

"I think for me today there were a lot of balls, especially ones that she overruled on some important points."

It was a sideshow to what as an enthralling contest between the top two British players.

Boulter's star has risen considerably since she won her maiden WTA Tour title here 12 months ago as she added a second, more prestigious title in San Diego and has broken into the world's top 30.

She will be targeting another long run after overcoming a titanic three-hour-and-13-minute battle against Dart.

Boulter said: "It's difficult, I know there is a lot going on, I'm trying to focus on myself and not get too involved in situations.

"There are some tough calls, but they do go both ways, I'm very cautious of that.

"That's half of tennis, keeping your cool and staying patient, I can say I am very proud of how I handled today, I stayed calm the whole time and that is really what won me the match, staying cool."

Earlier, Heather Watson enjoyed her first main tour-level win since February after she beat Kayla Day 4-6 6-0 6-4.