Jelena Ostapenko is a player that gets motivated by playing a player she personally doesn't like and she confirmed in a recent interview, she gets motivated more.
Ostapenko is a very unique personality in tennis because she doesn't really hide what she thinks. During the match Ostapenko can be seen making weird faces, questioning computer calls, arguing with umpires, her opponents and everything in between. She is also pretty famous for blatantly stating that she was better than her opponent during a post-match win. Recently she confirmed that facing players she doesn't like motivates her:
"When I play someone I don't like, Really want to beat her. That makes me wanna leave everything on the court. For the players that can work in different ways if you don't like someone and it's like your 'enemy'. Some might get distracted, emotional, and get annoyed very quickly. I'm the kind of a person that gets more focused in that kinds of situations.
To illustrate that we add a tweet which shows this quote in practice. Ostapenko never liked Wozniacki and her H2H against her is 4-0.