Canada's Eugenie Bouchard struck the first blow in her rivalry with Elina Svitolina, but since then it's all gone the Ukrainian's way.
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.
Federer downs Karlovic
Roger Federer made a victorious return Friday to the Sony Open after skipping last year's tournament, and then was treated to a tribute on the stadium video screen.
"It looks like a farewell video," Federer told the crowd with a laugh. "I miss one year, and you make me feel guilty."
Federer's back, as he showed by beating big-serving Ivo Karlovic 6-4, 7-6 (4). The Swiss star lost just three points on his serve to his 6-foot-11 (2.11-meter) opponent, and in a match with few rallies, he committed only three unforced errors.
Three-time champion Novak Djokovic followed Federer onto the stadium court and into the third round, defeating Jeremy Chardy 6-4, 6-3. Defending champion Andy Murray, playing for the first time since he parted with coach Ivan Lendl, rallied to beat Matthew Ebden 3-6, 6-0, 6-1.
Another three-time champ, Venus Williams, defeated Anna Schmiedlova 6-3, 6-3. Williams, the oldest player remaining in the women's draw at 33, is competing at Key Biscayne for the 15th time.
"It's good to be here still as an oldster," Williams said.
At 32, Federer has looked rejuvenated recently, and was the runner-up to Djokovic last week at Indian Wells. The 17-time Grand Slam champion says his new racket gives him more power, and he's moving as he did in the old days.
After falling out of the top five last year for the first time since 2002, Federer returned to No. 5 this week. He led from the start against Karlovic, making the surprising choice to receive after winning the toss and earning the lone break of the match in the opening game.
"I just felt like, you know, let him go first and see how it goes," Federer said. "It worked well today because I got the early break right away. That relaxed me for the rest of the first set clearly, but still he hung around."
While Federer had trouble with serves from Karlovic that peaked at 138 mph (222 kph), the Croat had no chance when returning. Federer won 49 of his 52 service points.
Federer improved to 11-1 in their head-to-head — or, in this case, head-to-shoulder. He said playing Karlovic presents unique challenges that he enjoys.
"Physically it's super easy. There are no long rallies," Federer said. "It's just more like a penalty shootout in soccer."
The longest point was the last one, and when Karlovic pushed a backhand into the net on the 10th stroke, Federer hopped happily in celebration and threw a fist.
The show of exuberance might be a hint he's keen to do well in a tournament he hasn't won since 2006.
"I'm very relieved and happy to be through," he said.
Djokovic converted all three of his break-point chances against Chardy, who was hobbled after hurting his right ankle in the penultimate game.
"When I was supposed to play my best and come up with some good serves and good shots, that's what I did in both sets," Djokovic said.
On the women's side, No. 2-seeded Li Na reached the third round when Alisa Kleybanova withdrew because of a viral illness. Kleybanova, who won in doubles Thursday, is a former top 20-player mounting a career comeback from Hodgkin's lymphoma.
No. 3 Agnieszka Radwanska, the tournament champion in 2012, defeated Romina Oprandi 6-0, 6-4. The Pole was hampered by a knee injury in her loss to Flavia Pennetta in the final at Indian Wells on Sunday, but showed no ill effects in her match Friday.
"I feel much better now, obviously," she said. "It's not perfect yet, but I think those few days I had of rest in between Indian Wells and Miami really helped me."
No. 6 Simona Halep, who lost to Radwanska in the semifinals at Indian Wells, withdrew because of a right toe injury.
Former world No. 1 Caroline Wozniacki advanced with a 6-1, 1-6, 6-3 win over Monica Puig, but No. 7-seeded Jelena Jankovic was upset by American Varvara Lepchenko.