US Open champion Alfie Hewett was one of four Britons to suffer defeat as the wheelchair tennis competitions got under way at the Australian Open.

Hewett, 21, lost 6-1 6-4 to Japanese world number one Shingo Kunieda, while Scot Gordon Reid was beaten 7-6 (10-8) 5-7 6-2 by Frenchman Stephane Houdet.

Lucy Shuker, a 2017 semi-finalist, was overwhelmed 6-0 6-0 by Dutch top seed Diede de Groot in the women’s singles.

Andy Lapthorne lost 6-1 4-6 6-4 to David Wagner in the men’s quad event.

• Williams knocked out by Pliskova
• Osaka beats Svitolina to reach semis
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Naomi Osaka dominated Elina Svitolina to win in straight sets and reach the Australian Open semi-finals.

The Japanese US Open champion had too much firepower for Svitolina, triumphing 6-4 6-1 in Melbourne.

Osaka, 21, hit 31 winners and took advantage of the second serve of the Ukrainian, who received treatment on her shoulder in the second set.

The fourth seed will face either Serena Williams or Karolina Pliskova in the last four on Thursday.

Svitolina, the sixth seed, is still to go beyond the quarter-finals at a Grand Slam.

“I tried to be consistent or as consistent as I can be. She’s really good but unfortunately she was injured. But playing against her injured was really tough,” said Osaka.

“For me, today, I had one goal – it was to try as hard as I can and not get angry.

“I didn’t do that well in the past two rounds, but I played well today.”

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Osaka announced herself on the world stage with her hugely impressive victory over Williams in September’s US Open final, although her achievement was overshadowed by the American’s outburst at umpire Carlos Ramos.

She has the chance to become world number one after this tournament and looked a class apart against Svitolina, who was affected by the shoulder problem which needed treatment during her third-round match.

There was no sign of an issue in the first five games as both players held serve, but the final five games of the first set were all breaks with Osaka striking the decisive blow when Svitolina netted a backhand.

The second set was much more straightforward, once a lucky net cord gave Osaka the first break in the second game.

Svitolina received treatment at the changeover when 3-0 down but to no noticeable effect and Osaka feasted on her weak second serve, winning 16 of 22 points on it.

The Ukrainian managed to halt a run of six games in a row for Osaka but a smashed winner sealed victory in one hour and 12 minutes.

When American tennis player Frances Tiafoe said pickle juice had helped him reach the quarter-finals of the Australian Open, plenty of people were a little taken aback/grossed out.

After all, who swigs the remnants of a jar of pickles to boost their sporting performance?

More people than you might think, actually.

Taking the Australian Open in isolation, two of the sport’s rising stars – Tiafoe, 21, and Russia’s Daniil Medvedev, 22 – have been spotted drinking it in Melbourne this week.

And widening the sample size a little, a photographer snapped Arsenal’s 22-year-old Uruguay midfielder Lucas Torreira drinking from a bottle labelled “pickle juice” in the Gunners’ 2-0 victory over Chelsea last weekend (although he did swiftly spit it out!).

Is this sport’s latest fad? And what is the science behind it all? BBC Sport finds out.

Tiafoe’s not-so-secret weapon

Unseeded Tiafoe was a surprise quarter-finalist in the Australian Open, and made further headlines with his choice of replenishment following that win over Bulgaria’s Grigor Dimitrov in the last 16.

Speaking about the gruelling four-set match, which lasted three hours and 39 minutes in the Melbourne heat, Tiafoe said: “I had the break, but started to feel my body.

“He played a good game to break me. After that, as you asked me, I was trying to stay alive. I was downing pickle juice, having that like Kool-Aid, just trying to get that done.

“I’m talking straight up: just downing it. It tasted terrible. I’m feeling terrible right now, man.”

The following day, Medvedev took time out from his match against Novak Djokovic to down some of the pungent fluid.

John Millman, the 2018 US Open quarter-finalist, was commentating on that match for television and was asked about the pickle juice.

“It helps the cramps,” said Millman. “There’s a lot of salt in it.”

When asked how it tasted, the Australian replied: “Terrible.”

It tastes bad… but does it actually work?

In a word: Yes.

Dr Mayur Ranchordas – a senior lecturer in sport nutrition and exercise metabolism at Sheffield Hallam University – has used the technique with professional cyclists and Premier League footballers.

And while, he says, the results are compelling, it is not necessarily for the reasons you might initially expect.

“Pickle juice contains sodium, potassium and vinegar and the obvious conclusion would be that it replaces sodium and salts lost when playing sport in a hot and humid environment like the Australian Open thus prevent cramping,” said Dr Ranchordas.

“However, how it really works is that it triggers a reflex in the mouth which sends a signal to stop muscles from cramping. That’s why it is drank at the onset of cramp.

“It stops cramping 40% faster than drinking water.”

Dr Ranchordas says it is particularly effective as a treatment for cramps in warmer conditions or when sporting occasions last longer than anticipated – be it a five-set tennis match or in extra time of a football game.

Just last month, India batsman Cheteshwar Pujara was shown grimacing on TV as he took the foul-tasting fluid on board during a marathon innings in oppressive heat in Adelaide.

What else is it good for?

The internet is full of stories of how pickle juice can cure alcohol-induced hangovers. One website even suggests pickle brine is the definitive hangover cure in some eastern European countries.

Throw in the fact it contains antioxidants, is said to help control blood sugar levels and boost gut health and you’re on to a winner next time you reach for a nice refreshing glass of the stuff.

And the craziest thing of all?

It is actually good for your breath, because it kills bacteria which breed in your mouth and create a stink.

Now you’re convinced, right?

Second seed Rafael Nadal eased past unseeded American Frances Tiafoe to reach the Australian Open semi-finals and continue his bid to win all four Grand Slams for a second time.

The 32-year-old Spaniard cracked 29 winners in a 6-3 6-4 6-2 victory.

Nadal broke 21-year-old Tiafoe in each of his first service games of the set.

The 17-time Grand Slam champion will play Stefanos Tsitsipas in the last four after the 20-year-old Greek beat Spain’s Roberto Bautista Agut.

“It is emotional to be back in the semi-finals,” said Nadal, who retired injured in his quarter-final against Marin Cilic last year.

“I had some troubles in this event so, after a while of not playing, to be back in the semi-final means a lot to me. I feel very lucky to be where I am after all the troubles I’ve been through.”

• Tsitsipas reaches first Slam semi-final
• Kvitova into first semi-final of ‘second career’
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Nadal dominates next generation

Nadal, who did have to stave off two break points at 2-1 in the second set, has not dropped a set as he aims to become the first man to win each of the four Grand Slams twice in the Open era.

Despite reaching at least the quarter-finals in 11 of his past 12 appearances, including four finals, he has only converted one of these runs into victory – his sole triumph at Melbourne Park in 2009.

And, despite not playing competitively since September’s US Open because of multiple injuries, he has cruised through his opening five matches.

Tiafoe, who celebrated his 21st birthday by reaching his maiden Grand Slam quarter-final on Sunday, could not cope with Nadal’s quality and intensity.

He had spent almost 12 hours on court coming into the match – more than three hours longer than Nadal – including his four-set wins over Wimbledon finalist Kevin Anderson and former world number three Grigor Dimitrov.

Nadal broke again for a 5-2 lead in the third, going on to serve out victory in one hour and 47 minutes.

The Spaniard used his trademark forehand to great effect, particularly down the line, hitting 13 winners on that side.

“The serve and winner with the first forehand is something very important for me, very important today, but also very important if I want to keep playing for a few years,” he said.

“It has given me a lot of free points and that is so important at this stage of my career.”

• Djokovic confident over fitness after gruelling Medvedev win
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Tsitsipas, 20, followed his last-16 victory over defending champion Roger Federer with another four-set win over Spain’s Roberto Bautista Agut earlier on Tuesday.

Nadal has beaten the Greek in straight sets in both of their previous meetings – in ATP finals on clay in Barcelona and the Toronto hard-court last year.

“It is going to be a great year to be sharing generations, that’s what makes this sport special – let’s see what happens,” Nadal said.

“During the last year he has been improving every month. He has already won a tournament and now in the semi-finals and able to win against best players in the world.

“He is unbelievable today but he has the chance to be one of the best for a long time.”