Kasatkina has been one of the fortnight's feel-good stories, but the emotional and physical exertions finally caught up with her as Pliskova ran out a 6-3. 6-2 winner.
Pliskova, the No.18 seed, took full advantage of the friendly conditions, hitting winners at will past her weary teenage opponent. However, it was far from mindless ball-bashing from the Czech, who gave Kasatkina very little in the way of cheap points, coughing up 10 unforced errors during their hour on court.
Kasatkina held her own in the first set, withstanding the onslaught from the other end until the sixth game when Pliskova arrowed a forehand into the corner to break. With Pliskova's own serve as dominant as ever, the set was soon in the bag.
Pliskova continued to turn the screw at the start of the second, another thumping forehand bringing an immediate break as she hurtled towards a maiden Indian Wells semifinal.
While Kastakina was unable to replicate the tennis that accounted for No.12 seed Timea Bacsinszky a round earlier, it takes little away from a remarkable rise; this time last year, the teenager, then outside the Top 300, was slogging it out on the ITF Circuit.
"Now I'm Top 40," she said in her post-match press conference. "Last year I was 340. Yeah, it was pretty fast!"