Andy Lapthorne had plenty to be proud of on the opening day of the Australian Open wheelchair tennis events.

The Briton claimed the first match win in the expanded eight-strong quad singles draw at Melbourne Park – a first for a Grand Slam event, which until this year have featured four players – beating David Wagner 6-1 6-4 to book his place in the semi-finals.

“Dylan [Alcott] pipped me at Wimbledon by about 20 seconds when we were racing each other to see who could be the first one to win a match at Wimbledon,” Lapthorne said. “So I’m going to go back into the locker room now and let him know that I was first to win a knockout match at the Aussie Open! It’s always good to get one back on him.”

The move to expand the quad field at the majors to eight players, bringing it in line with the men’s and women’s open wheelchair events, is a subject close to Lapthorne’s heart – and the day’s action at Melbourne Park serves to underscore that conviction.

“This is what all the campaigning has been for, to give the other guys an opportunity, and they’ve taken it with both hands,” said the 30-year-old. “Now someone like Niels Vink has got a career ahead of him of 10 or 15 years where he’s going to be on an equal footing with all the other wheelchair players. For me, that’s bigger than any win or any Grand Slam. When I was his age, there were a lot of doors that were closed, and I’m so proud that they have opened. Hopefully Roland Garros and Wimbledon will follow suit.”

On court, Lapthorne – who has been open in discussing the mental struggles he has faced over the past year – was pleased to come through a match that seemed to be on his racquet until the loss of a couple of games while leading 6-1 3-0, and credited a fresh outlook and approach to his preparations for his fired-up demeanour on court.

“With the way I’m feeling right now, I want to win every match 6-0 6-0 so I don’t have to come up against any mental demons,” he admitted. “You don’t want to let David start dominating the court. He can be a silent assassin – if you go quiet he can take control of the court, roll around and pick you off.

“I’ve got Joe Gill out here working with me, and we made an agreement at the start of this week the old Lappo comes out on court to give it a go. If the tennis follows, the tennis follows, but make sure the attitude on court is right.

“I met up with some friends and watched a match on Rod Laver Arena on Friday, which is something I don’t usually do during a tournament. I’m just doing things a bit differently, trying to stay relaxed and have fun out here. I’m aware that it’s a privileged position we’re in, playing tennis while the rest of the country is locked away and the UK is locked away. It’s a privilege to be here, and I’m not going to waste the opportunity.”

Up next for Lapthorne is US Open champion Sam Schroder, who battled back from a set down to beat Japan’s Koji Sugeno, the Dutchman advancing 2-6 6-3 6-3.

Dylan Alcott’s quest for a seventh successive Australian Open crown began with a 6-0 7-5 victory over compatriot and close friend Heath Davidson, a bittersweet win for the defending champion.

“It’s very hard to play one of your best mates,” said the 30-year-old. “I always struggle with it. If you're playing a final it's a bit easier, because you both got through. If it's the first round, you're like, bummer.”

Up next for the top seed is 18-year-old Dutch Grand Slam debutant Vink, who opened with an imperious 6-0 6-0 victory over US wild card Nick Taylor.

“He's 18 and he's bloody awesome,” Alcott said. “We're actually really good mates, too. We played each other in a final before the French Open. We both didn't have coaches, so we actually warmed each other up for the final that we were both playing each other in. He's an awesome young guy. I'm really excited about the opportunity to play him.”

In the men’s singles, defending champion Shingo Kunieda launched his bid for an 11th Australian Open title with what he described as “an almost perfect match,” a 6-0 6-1 victory over Aussie wild card Ben Weekes.

The world No. 1 will face Alfie Hewett in the semi-finals after the Briton beat Nicolas Peifer 7-5 6-3, while in the bottom half Joachim Gerard downed Stephane Houdet 6-3 7-6(8) to set up a semi-final clash with Gordon Reid, who upset No. 2 seed Gustavo Fernandez of Argentina 5-7 6-4 6-4.

"It was a gutsy final set – it wasn’t always pretty, but sometimes you’ve got to do that when you’re not feeling 100%," said Reid, whose preparations were hampered by a sore neck and stomach bug in the days leading up to the tournament.

"I wasn’t sure I was going to be able to play a couple of days ago, even yesterday, so I was glad just to be out there enjoying it, making the most of it, and obviously really happy to come out on the right side of the result."

Women's top seed Diede De Groot came out on top against Dutch compatriot Aniek Van Koot 6-0 3-6 6-4 to set up a semi-final clash with Japan's Momoko Ohtani, who eased past Great Britain's Lucy Shuker 6-2 6-2.

Defending champion Yui Kamiji will face Kgothatso Montjane of South Africa in the other semi-final after beating Chile's Macarena Cabrillana 6-0 6-1. Montjane booked her spot with a 6-1 6-2 victory over Colombia's Angelica Bernal.

"I’m feeling pretty good, pretty confident," said Montjane, though to her second Australian Open semi-final. "I played Yui last week in the semi-final of the Melbourne Open, and took a lot of positives from that. If my serve works well that’s when I can create opportunities, and I think my return game is strong too, so if I can avoid errors it will be a match."