"It's tough to play first round against the opponent you played last year in semifinals," she said in her post-match press conference. "But it was a good match, we played solid and I'm happy about the result."
Bencic reached the final at this very tournament one year ago, becoming the youngest Top 10 debutante since Caroline Wozniacki in 2009. Since then, the Swiss youngster has been beset by injuries, causing her ranking to tumble out of the Top 100 on Monday's rankings.
Still, the teenager showed signs of promise to start the year, pushing eventual Australian Open champion Serena Williams to two tough sets in Melbourne. She and Kasatkina had split their first two meetings last year, winning their St. Petersburg semifinal before the Russian got her revenge at the Kremlin Cup in the fall.
Beyond being rivals, the pair are good friends, hanging out together at the Player Party.
"I think there is friendship on the tour! Because we spend together so much time - 30 weeks of the year - so you have to have some fun with the girls you know. We came up together in juniors, from 16 or 17, so we cannot surprise each other on court."
Kasatkina started the year with a career-best win over then-World No.1 Angelique Kerber, but was looking to shake off a surprising first round loss at the Australian Open. Exchanging early breaks of serve, the No.8 seed emerged victorious from the early skirmish to take the first set in 34 minutes.
The second set similarly saw service breaks to start, but Bencic got far closer to leveling the match as it headed towards the critical stages, holding a break point at 4-4 that would have allowed her to serve for a decider.
Kasatkina gamely dug out of that game and ultimately eased into the second round on her second match point. Standing between her and a second straight St. Petersburg quarterfinal is wildcard Natalia Vikhlyantseva.
"We played once in juniors. She's changed her game a little, so it will be a difficult match and I'll need to prepare well."
Earlier in the day, defending champion and No.6 seed Roberta Vinci won a St. Petersburg rematch against Timea Babos. A year ago, the Hungarian youngster led Vinci by a break in the final set, and found herself in the same position on Tuesday against the Italian.
From 3-1 down in the decider, Vinci lost just one more game and booked a second round clash against qualifier, former Top 10 player Andrea Petkovic.
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This article was first seen on www.wtatennis.com.