Kristyna, who is two minutes older than her twin, came through three rounds of qualifying and beat Viktoriya Tomova in the opening round of the main draw to set up a first meeting with her sister since the Eastbourne qualifiers six years ago.
"It is tough to compete at 100% when you're not really sure you want to beat your sister," Karolina told reporters. "We're in touch all the time and share a room here.
"We have been hitting everyday and warming up for matches. We share a lot of things and are always on the phone if we are playing different tournaments."
Kristyna, ranked 112th in the world, has not enjoyed the same success as her twin and has not won a title since her maiden triumph at the Tashkent Open in 2016, but beat Karolina the last time they faced each other across the net.
"It is (the first meeting) in like six years, so it's like from the beginning," Kristyna said. "I think it was different before and also the tournaments were small, so you don't really see it. I think this one will be more stressful.
"It's family, so you don't want (to face) her... but still I want to win as well."
(Reporting by Hardik Vyas in Bengaluru; Editing by Simon Jennings)
