Now in California, the sisters are pairing up again to play Irina Camelia-Begu and Monica Niculescu of Romania.

"I would say we are more like friends," Dayana told BBC Sport.

Dayana is 21, but Ivanna is just 15. So the older sister has had to take on some parental responsibilities as well.

"Before, I don't remember when we were spending that much time together, or travelling together, and it's a pretty high responsibility on me now," she added.

"I'm trying my best. I'm trying to make some fun so she can feel pretty relaxed. She looks very tall and big, but inside she is very small and she misses her parents.

"When I lost the final in Lyon we went back to the room - she started to cry and saying I want to go home, I want to see the parents. And I felt also very bad and I had to try and calm her down."

When the Russian invasion of Ukraine began, the sisters spent two nights sheltering with their parents in an underground car park in Odessa, a southwestern city on the Black Sea.

Their father decided they should leave the country as soon as possible, and so they made their way to the Romanian border on the Danube river with their mother.