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Katie Boulter used her forehand to devastating effect against Makarova

Australian Open 2019 Venue: Melbourne Park Dates: 14-27 January Coverage: Daily live commentaries on the BBC Sport website, listen to Tennis Breakfast daily from 07:00 GMT on BBC Radio 5 live sports extra and watch highlights on BBC TV and online from 19 January.

Britain's Katie Boulter reached the Australian Open second round despite forgetting the rules in the tournament's first final-set tie-break.

Boulter, 22, thought she had won after reaching seven in the decider against Russian 2015 semi-finalist Ekaterina Makarova and celebrated accordingly.

"I forgot it was first to 10," said the British number two, who composed herself to win 6-0 4-6 7-6 (10-6).

But fellow Britons Harriet Dart and Heather Watson suffered heavy losses.

Dart, 22, fell to a chastening 6-0 6-0 defeat by five-time Grand Slam champion Maria Sharapova as they opened the tournament on Rod Laver Arena.

Watson, 26, fared little better, losing 6-1 6-2 to Croatian 32nd seed Petra Martic in hot conditions that she said had made her feel light-headed.

Boulter will face another tough test in the second round when she plays Belarussian 11th seed Aryna Sabalenka on Wednesday.

Boulter comes out firing

Boulter came to prominence when she won her first Grand Slam match at Wimbledon last year. Since then she continued to climb up the rankings and broke into the world's top 100.

That enabled the 22-year-old from Leicester to gain direct entry into a Grand Slam main draw for the first time in Melbourne - and she demonstrated her talent against 30-year-old Makarova.

"Being here on ranking gives me confidence," Boulter said.

She hit 53 winners - compared to just 16 from the other side of the net - in a powerful display which showcased her ferocious forehand.

The Briton, who is ranked 97th, needed just 26 minutes to take the first set as Makarova looked a shadow of the player who reached the 2014 US Open semi-finals and the last four in Melbourne four months later.

Makarova - now ranked 60th in the world - recovered to edge a tight second set, clinching it with a break to love as Boulter's service game disintegrated.

But Boulter possessed a steely determination and used that to dig deep on several occasions in the final set.

The pair traded breaks to stay level midway through the set, before Boulter missed four break points in a marathon game which Makarova eventually held for 4-3.

Boulter saved two herself in the following game, then missed another for a 6-5 lead, but put that behind her to come out firing in the tie-break.

With a pro-British crowd behind her, she raced into a 5-0 lead and, after the premature celebrations at 7-4 ahead she regained her focus to win in two hours and 24 minutes.

"I ended up getting the win, I probably would have been devastated had I not," Boulter said. "But I've got to take it light-heartedly now. At least I know the rule now.

"It's very tough to turn around because you've released and think you've won the match.

"Then you have to get back to work and dig deep. I'm pretty proud of myself."

Nerves got the best of me - Dart

Harriet Dart is ranked 131st in the world

Dart won three matches last week to qualify for a place in the main draw of a Grand Slam for the first time, being rewarded with a tie against her "idol" Sharapova.

But she says she was overcome by nerves on Melbourne Park's 15,000-capacity show court Laver.

The Londoner only won 29 points as Sharapova, seeded 30th, needed just one hour and two minutes to reach the second round.

"I think nerves got the best of me but I tried my best and that's all I could do," Dart told BBC Sport.

"She hits a huge ball and it comes at you quick. She doesn't give you anything so it was always going to be difficult.

"I'm glad to have these experiences and hopefully get more of big experiences on big stages."

Watson 'needs to improve mental part'

Heather Watson received treatment during her defeat by Martic, saying she felt dizzy and light-headed because of the heat

Watson was tearful when she spoke to the media following her third successive first-round defeat at a Grand Slam.

The former world number 38, who is now outside the top 100 and was replaced by Boulter as British number two on Monday, did not rule out hiring a sports psychologist to improve the mental side of her game.

"The mental part is really important. I feel everyone here can play tennis but it is about confidence and believing," she told BBC Sport.

"I am going to look into anything I can improve on."