"Diva," Serena wrote alongside one snap of her sister walking through the aisles during the pair's shopping trip, showing off her chic black-and-tan outfit, before making her objection to the look clear.
While Serena poked fun at her big sis on Wednesday, there's really nothing but love between the two.
In fact, the 35-year-old tennis star thanked Venus after beating her in the finals of the 2017 Australian Open last month.
"I really would like to take this moment to congratulate Venus," Serena gushed. "She's an amazing person. There's no way I would be at 23 without her. There's no way I would be at one without her. There's no way I would have anything without her."