"I knew it would be like that because we practised a few days ago and she beat me in practice", she added.
"I'm just going on court and actually now enjoying every minute during I'm playing", 20th seed Kasatkina told reporters.
However, after receiving a pep talk from coach Darren Cahill at a change of ends, Halep raised her level to reel off three successive games and take the opener 7-5, although she was forced to save a break point before wrapping up the set at the fourth attempt with an unreturned serve.
She said Serena Williams - who made her return at this year's tournament after having a baby in September - "should have been seeded number one, because she left as number one in the world".
Halep is the only former Indian Wells victor left in the women's draw after World No.20 Daria Kasatkina upset World No.2 Caroline Wozniacki 6-4, 7-5.
Jim Bowen, 'Bullseye' host, dies at 80
He told BBC Radio Lancashire in 2017, "I watched seven hours of Ken Dodd and I watched him completely decimate 7,000 people". But he found fame with the much-loved ITV show Bullseye . "I'd look at that photograph and say, 'Jim, you're a lucky lad'".
Simona Halep came through a stern test from Petra Martic in the wind to reach the semi-finals of the Indian Wells Masters.
Halep said she "dominated a little bit more" against Wang than in her previous match, in which she lost the first set against world number 165 Caroline Dolehide, a 19-year-old American. And also, you know, I have many things to learn from them.
While Halep overcame a sluggish start to beat Wang Qiang 7-5 6-1, Australian Open champion Wozniacki fell to the same player who knocked her out of last month's St. Petersburg Ladies Open.
"I missed too many shots in the first set".
"And, yeah, I'm playing (my) best matches against the best players". Williams, who is the oldest female player in the draw at 37, will face either wild card Danielle Collins or World No.27 Carla Suarez Navarro of Spain in the last eight.
The 26-year-old is yet to win a Grand Slam title but underlined her resilience in testing circumstances to recover from a break deficit in the final set and set up a meeting with either world No 5 Karolina Pliskova or Japan's Naomi Osaka.