Serena Williams' young daughter, Alexis Olympia Ohanian Jr., is already showin' she's got tennis in her DNA ... the 4-year-old hit the court to work on her backhand.
Video of the training sesh was posted Monday ... showing Alexis in her sports gear, executing a picture-perfect backhand.
Keep in mind, she's only 4-years-old!!
"Practice makes progress," the caption read on the video posted to Alexis' Instagram (BTW, she has 631K followers) ... and fans went crazy in the comments over the resemblance to her 23-time Grand Slam winning mom, Serena.