Kasatkina's run to last week's Indian Wells quarterfinals turned heads, but on Thursday night against the dominant Romanian she just couldn't come up with the same brand of giant-slaying tennis that has seen her climb up the rankings.
But right as it seemed like Halep would have a smooth path to victory, the Russian took advantage of her momentary lapse in the second set to begin to mount a comeback.
"I think I complicated it a bit in the end of the match," Halep admitted afterwards. "I did a few mistakes and I was rushing a little bit.
"I did everything - I win and lose the points. That was it."
With a 5-2 lead for Halep in the second set, a handful of unforced errors from the Romanian gifted Kasatkina a hold to stay in the match. The Russian took off from there, taking the next two games and looking ready to send the match into a deciding set.
Halep had other ideas though, and proved why she scored more hardcourt wins last year than any other player by finding another gear in time to stop the surge and clinch the victory, 6-3, 7-5. Halep's 24 winners were too much for Kasatkina, who hit just 10 winners to 41 unforced errors.
Despite the near-scare, the Romanian had nothing but praise for her 18-year-old opponent:
"She's a young player, she plays really well," Halep said. "She has time to improve her game."