World number 82 Kartal, who reached the fourth round at Wimbledon for the first time this summer, has won all three of her BJK Cup ties since making her debut earlier this year.
Kartal was confident and in control from the outset against Shibahara, claiming back-to-back breaks on her way to racing into a 4-0 lead.
Shibahara looked nervous early on but shifted the momentum her way when she won eight points in a row to claw back to 4-3.
But with a break still behind her, Kartal halted Shibahara’s run with a hold to love that unsettled her opponent once more. Mistakes crept in on the Japanese’s service game, allowing Kartal to take advantage and clinch the opening set.
The second set was a far closer affair, and Kartal had to dig deep to fend off a break-point chance at 4-4.
Although she could not break the obstinate Shibahara’s serve, Kartal dominated the tie-break, securing victory on her second match point.
“Their [Japan’s] whole team is super tough so I knew it was not going to be easy in the slightest,” Kartal said.
“I tried to play my game when things got tough and stay aggressive. I backed myself all the way.”
