It's all about the pair's 'vlogging' talent with the two of them delighted to wind each other up over their respective skills behind the camera and on the mike when they're working on Kasatkina's popular YouTube channel "What the Vlog".
Giving its viewers an entertaining inside peek at the tennis scene, Kasatkina, who set up the channel with her figure skater girlfriend Natalia Zabiiako, has given her fourth-round opponent Andreeva the chance to film the odd item for them too.
And it led to the opponents previewing their Paris clash on Monday with some unflattering banter about their respective media skills.
Asked what she thought of Kasatkina as an interviewer, Andreeva responded amid some laughter: "I think she can improve."
On hearing this, Kasatkina who had already joked "I hate her" about the uber-talented 18-year-old world No.6, doubled down in mock horror: "I was right. I hate her!
"Well, Mirra is not the one to talk about it because actually she had opportunity to interview players in our Rome vlog, so she took the camera, and went to talk with someone in the players' restaurant. It was terrible!
"Also, the filming skills were not on point, so she needs to learn."
Then, they were keen to point out that, actually, this knockabout stuff was just the way they communicate with each other.
"You know, we're just giving little s--t to each other all the time, just joking around," said Kasatkina.
"We are very good with each other. We were having ice bath together right now a couple of hours ago after our (third-round) matches."
When it comes to tennis, though, Kasatkina admits there's not much she can teach this soar-away French-based phenom Andreeva.
"The only thing I'm helping her, it's to get on the vlog," Kasatkina said. "Honestly, Mirra, she's a very nice girl and an amazing player. We've been quite good with each other. I can even say that I think we are kind of friends.
"She's super young and super talented, so she will achieve a lot of things."
The two Russian-born players have practised regularly but only played once last October in a final in Ningbo, China, won by Kasatkina in three sets.Â
"A big drama match," says the Australian, perhaps recalling how she ended up consoling the youngster, who was in floods of tears after letting a 3-0 lead slip in the final set.
So what will she have to do to beat Andreeva?
"I have to run a lot," she said. "Going to be long rallies. Mirra, she's not giving anything for free. You know, to get every point, I'll have to die on court. I'm ready for that."
