Harriet Dart calls out umpire in loss to Katie Boulter at Nottingham Open with Heather Watson also through to last 16

Harriet Dart offered to bet the umpire £50,000 she was right about a disputed line call in her ill-tempered defeat to British team-mate Katie Boulter at the Nottingham Open.

Dart said to the official Kelly Rask that she was “embarrassing yourself” after the British No 2 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.

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 battle against Dart that lasted three hours and 13 minutes.

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

What’s coming up on Sky Sports Tennis?

In the run-up to the third Grand Slam of 2024 – Wimbledon – you can watch all of the biggest tennis stars in action live on Sky Sports as they compete across the grass-court season.