After five winless years on the tour, the 21-year-old Halep has caught fire in 2013, notching four titles including the US Open hard court run-up event in New Haven last week.
"It was the best match ever for me," Halep said after a lightning-quick demolition of Kirilenko that took just 51 minutes. "I played incredible today. No mistakes."
Pardon Halep for the slightest of exaggerations as the aggressive baseliner was charged with eight unforced errors, though her helpful opponent committed three times that number.
For Kirilenko, it was a case of once again hitting a third-round barrier at the US Open.
The Russian had reached the round of 32 at Flushing Meadows for the eighth time but only once has she gone beyond, with a fourth-round appearance against eventual winner Samantha Stosur in 2011.
The victory put the former French Open junior champion into the round of 16 for the first time at a Grand Slam.
She will face Italy's Flavia Pennetta, a 7-5 6-1 winner against 2004 US Open champion Svetlana Kuznetsova following her upset of fourth-seeded compatriot Sara Errani.
Halep was hard-pressed to explain her brilliant run.
"I am more aggressive, more relaxed on court," said Halep, who has recovered from a variety of nagging injuries. "I just want to take the pleasure of every point and fight for every point.
"I feel good, and I play really, really good now."
The Romanian, who ended last year ranked 47th, has soared up the rankings list, climbing into the top 20 at number 19.
After a mediocre start to the year, Halep caught fire in June, winning her first tour titles at Nurnberg and 's-Hertogenbosch, then adding another crown at Budapest in July.
A lower back injury forced her to withdraw from the Toronto event this month, but she came back to reach the quarters at Cincinnati before falling to world number one Serena Williams.
Halep said beating Czech Petra Kvitova in the final to cap another title run last week gave her a big boost.
"I played really good in New Haven, a good week, the best week in my life," said Halep. "When I came here, I just wanted to keep my energy on."
Halep cleared a difficult hurdle in her opening match at Flushing Meadows.
"My first match was very difficult because (Briton Heather Watson) had set and 4-3. But I came back," she said.
Halep followed that with a 6-2 6-1 thrashing of Croat Donna Vekic, then Saturday's rout of Kirilenko.
"I'm happy that I can win a lot of matches here. I played really good. I want to enjoy this tournament," said Halep, hoping the magic ride has miles to go.
"I feel good. I just want to keep going."
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