Roger Federer was already a long way clear at the top of the list of men with the most wins in Grand Slam singles matches, so becoming the first to 300 wasn't a major distraction.
He reached the milestone at Rod Laver Arena on Friday, when he moved into the fourth round of the Australian Open with a 6-4, 3-6, 6-1, 6-4 victory over Grigor Dimitrov.
"It's very exciting, I must tell you," Federer said of his latest record, adding that reaching 1,000 wins in tour matches last year was also a cause for celebration. "It was a big deal for me.
"Not something I ever aimed for or looked for, but when it happens, it's very special. Yeah, you look deeper into it, I guess, where it's all happened and how. So it's very nice."
Defending champions and top-ranked Serena Williams and Novak Djokovic had matches starting at the same time on nearby courts.
Six-time champion Serena Williams raced to a 6-1, 6-1 win in 45 minutes over 18-year-old Russian Daria Kasatkina on Rod Laver Arena. She will next play Margarita Gasparyan, who beat Yulia Putintseva 6-3, 6-4.
Djokovic took 25 minutes to win the first set against No. 28-seeded Andreas Seppi but needed almost an hour in the next two, saving two set points in the tiebreaker before winning 6-1, 7-5, 7-6 (6) win on Margaret Court Arena. After making way for Williams on the main court, he noted it was his first match on Melbourne Park's No. 2 court since it was renovated to include a roof.
Djokovic has won five Australian titles and his victory maintained a streak of reaching at least the fourth round at every major since the 2009 French Open. He was also particularly wary of a third-rounder against Seppi, who beat four-time champion Federer at the same stage here last year.
Seppi "is not overwhelmed by the occasion of the big courts, he knows how to play the big stage. He beat Federer last year here in the Australian Open, so he knows how to play big matches," Djokovic said. "He's very dangerous. I'm just glad to get through in straight sets."
Kei Nishikori had a 7-5, 2-6, 6-3, 6-4 win over No. 26-seeded Guillermo Garcia-Lopez and will next play 2008 Australian Open finalist Jo-Wilfried Tsonga, who beat fellow Frenchman Pierre-Hugues Herbert 6-4, 7-6 (7), 7-6 (4).
Nishikori reached the 2014 U.S. Open final and the quarterfinals at the Australian and French Opens in 2015 before withdrawing from his second-round match at Wimbledon with an injured left leg.
No. 15 David Goffin beat No. 19 Dominic Thiem 6-1, 3-6, 7-6 (2), 7-5 — his first win against a top-20 player at a Grand Slam. He faces a tougher proposition next: Federer.
The 17-time major winner now is 67 clear of No. 2 Jimmy Connors in Grand Slam singles wins, though Federer's main aim is to win his first major since Wimbledon 2012.
He improved to 5-0 against Dimitrov, a young Bulgarian with a similar style.
Dimitrov needed treatment at times, but Federer didn't cut him any slack — he lost in the third round here last year, his worst run at Melbourne Park since 2001.
"You're aware of it — I'm a veteran so I," don't get distracted, Federer said. "I've been fooled too many times when I was a teenager. I hope he's OK."
Earlier in a rain-interrupted day at Melbourne Park, 2008 Australian Open champion Maria Sharapova collected her 600th win at tour level.
She advanced with a 6-1, 6-7 (5), 6-0 win over Lauren Davis before she was reminded of the milestone, becoming the 17th woman to reach the mark.
"Wow. I've won 600 matches?" Sharapova said. "I think it's a proud number."
The fifth-seeded Sharapova will next play No. 12 Belinda Bencic, who beat 4-6, 6-2, 6-4 against Kateryna Bondarenko.
Roberta Vinci, who ended Williams' bid for a calendar-year Grand Slam in 2015 with a shocking semifinal win at the U.S. Open, lost 0-6, 6-4, 6-4 to Anna-Lena Friedsam.