Bouchard went down to a 1-6, 6-1, 6-2 defeat at the hands of Svitolina in her opening match at the Sony Open on Friday.
Bouchard got the rivalry going two years ago when she won the junior Wimbledon title over Svitolina.
Since then, Svitolina has beaten Bouchard three straight times, including at Indian Wells and in a Fed Cup tie in 2013.
Montreal's Bouchard had an impressive start Friday but was quickly overcome by Svitolina, who spent 98 minutes engineering her comeback, The winner broke Bouchard five times and profited from six Bouchard double-faults.
Bouchard ended with a return error on her opponent's first match point.
"I played really well in the first, set, I was doing everything I wanted to do. But in the second and third my level went down," Bouchard said.
"All the balls I was hitting well in the first set were going out, I was missing much more. She's a good player who fought and stayed in the match."
Bouchard's life on court has been a challenge since reaching the Australian Open semifinals two months ago, Her best showing since was an Acapulco quarter-final last month before going out in the fourth round at Indian Wells to Simona Halep, the newest member of the top five on the WTA circuit.
"There is more pressure but it shows that I'm a target, the one the other girls want to beat," Bouchard said.
"It shows that I'm moving up and having more success. I feel it all more but it's the path I want to be on."
Bouchard got off to an early break over Svitolina in the first set and managed to hold on in a roller-coaster win to take the early lead.
But Svitolina slowly began reversing her position, drawing errors form Bouchard and breaking twice in the second set. Svitolina levelled at a set apiece after Bouchard saved four set points but returned long on a fifth.
The third set was one-way traffic against Bouchard as the Canadian lost serve in the third and seventh games before her opponent served out the upset.