Grigor Dimitrov stayed on course for his title defence but women's second seed Emma Navarro was stunned by local favourite Kimberly Birrell at the Brisbane International on Wednesday.
Two-time men's champion Dimitrov downed Aleksandar Vukic 6-2 7-6(5) to advance to the quarter-finals, overcoming late resistance from the Australian wildcard.
"It's such a home atmosphere, honestly. It doesn’t feel like a tournament to me," the Bulgarian said.
"That's why I think the excitement is different. My attitude I think also changes quite a bit. It's a very special week."
Birrell gave the local fans something to cheer about as she pulled off the biggest win of her career, beating Navarro 7-5 7-5.
Egged on by the vociferous crowd at Pat Rafter Arena, the 113th-ranked wildcard broke to serve for it at 5-4 in both sets before closing it out on her second attempt.
"I've spent so many hours on this court since I was little," the 26-year-old said.
"I watched the Brisbane International when I was a kid and to get to play here and have the tournament that's basically at home is so special."
The journey of Novak Djokovic and Nick Kyrgios as a doubles pair ended with a 6-2 3-6 10-8 defeat by top seeds Nikola Mektic and Michael Venus, who advanced to the quarter-finals.
Kyrgios, playing his first tournament since a wrist surgery in September 2023, was beaten by Frenchman Giovanni Mpetshi Perricard in a battle of big servers in men's singles on Tuesday.
The Djokovic-Kyrgios duo came within two points of a win but an untimely double fault in the match tie-break allowed Mektic and Venus to clinch the nailbiter.
"Down three points in the match tie-break it wasn't looking great, but somehow we got back in there and Mekta hit a great return on match point," Venus said.
Daria Kasatkina overcame Peyton Stearns 7-6 4-6 7-5 in a slugfest lasting nearly three-and-half hours.

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