The imported Aussie 'Dasha' continued her welcome revival but had to really sweat it out on another scorching day at Roland Garros before subduing her dogged second-round opponent, Swiss qualifier Susan Bandecchi, 7-5 7-6 (13-11) on Thursday.
In an epic second-set tiebreak lasting 17 minutes, Kasatkina eked out seven match points before finally killing off the stubborn challenge of the big-hitting world No.215 to ensure she'll be in the last-32 of the women's singles, while Alex de Minaur will play his third-round match on Friday against Jakub Mensik.
But two days after the performances of their lives -- Gold Coast's Birrell downing women's fifth seed Jessica Pegula and Home Hill's Walton knocking out men's sixth seed Daniil Mevdevev -- their follow-ups fell flat against seemingly more beatable opponents.
Birrell was initially bamboozled and eventually outlasted by unorthodox Oleksandra Oliynykova, succumbing to 'double trouble' as her serving faltered and she folded in a 10-point tiebreak decider 6-3 0-6 7-6 [10-5].
Soon afterwards, Walton, definitely not as sharp after his five-set duel with Medvedev, was largely outclassed by American Zachary Svajda, who had beaten Alexei Popyrin in the previous round and again proved the Aussie slayer in a 6-3 6-4 6-7 (4-7) 6-2 win.
Just as against Pegula, the 28-year-old Gold Coast fighter Birrell produced a stirring fightback but found the all-court variety of the crafty Oliynykova a much different challenge, a puzzle which she eventually couldn't solve.
After looking a little bewildered in the opening stanza, it appeared Birrell had cracked the code, latching onto the moon balls, drop shots and loopy slices to whitewash the increasingly weary-looking Ukrainian in the second.
But Oliynykova was far more solid in a see-saw decider, before 28-year-old Birrell threw in two more double faults in the decider as the pressure increased, taking her overall tally to a very costly 11
Oliynykova even daringly delivered an underarm serve on match point, eventually winning that decisive point after nearly two-and-a-quarter hours.
Watched by the close family friends who've made Paris like a second home for her, Birrell still managed to raise a smile afterwards as she sighed: "Tennis is quite a roller-coaster sometimes, and you can have one of the best days of your life followed by one of the tougher, tougher days.
"But although today was tough, I'm still really proud of myself, the way I fought. I gotta keep my head up and keep moving forward, and remember all the good parts of this week when I've played some of the best tennis that I've ever played.
"So I definitely need and want to take confidence from that, just remind myself I have that in me."
Walton, too, had much to enthuse about after the biggest win of his career, but shrugged nothing had really changed for him.
"Like, I beat Medvedev, ate here, went back to the Airbnb, and did my nightly sudoku, and didn't do anything different whether I'd lost to him or beaten him," smiled Walton.
"I still went to bed the same person, and it doesn't change, doesn't change your life. Just went about my business as usual."
He did, though, manage to also solve the sudoku...
