MASON, Ohio -- Naomi Osaka's first WTA tour appearance since the French Open in late May did not last long.
The second-ranked Osaka sprayed balls all over the court in a 3-6, 6-3, 6-3 loss to No. 76 Jil Teichmann on Thursday at the Western & Southern Open.
Osaka repeatedly punched her left thigh with her left wrist and talked loudly to herself, trying to get herself going, but she was impassive as she shook hands at the net with the exuberant Teichmann.
"I think sometimes the scoreline in tennis can fool you," Barty said. "Though it seemed like a quite convincing scoreline in the match, each and every game had crucial points and I was able to win most of those."
"It was definitely a great level of tennis," said Medvedev, the 2019 champion and last year's runner-up to Novak Djokovic. "It was pretty hot for both of us. I saw Grigor struggling, so I figured that's how it is. It's the same for everybody. Our bodies are getting more used to the heat."
Former tournament women's champion Karolina Pliskova advanced with a 6-4, 7-6 (5) win over Jessica Pegula. Olympic champion and third-seeded Alexander Zverev also moved on, beating Guido Pella 6-2, 6-3, while Roland Garros finalist and second-seeded Stefanos Tsitsipas was pushed by Lorenzo Sonego to three sets before prevailing 5-7, 6-3, 6-4.
Medvedev bounced back after a nasty fall early in the second set to close out the win.
"You can't see this on video, but my racket got between my legs and hit the back of my calf," Medvedev said. "I don't know how that happens. I actually have a bruise on my calf. A bruise is a bruise. It's nothing serious."
The second-ranked Russian, the winner last week in Toronto, won when Dimitrov double-faulted on match point. Medvedev has been on the court for only 2 hours, 28 minutes while winning his first two matches in straight sets after a first-round bye.
Medvedev is the first player not named Djokovic, Roger Federer, Rafael Nadal or Andy Murray to crack the top two since July 18, 2005. Injuries and other issues have limited Djokovic, Federer and Nadal this year.
While his matches have been short, Medvedev feels winning will go a long way.
"The more matches I can win in these two tournaments that are similar to New York, the more confidence you have," he said. "Confidence is the big key. It's good coming there knowing that you're capable of playing good. Now, I know it's possible. A Grand Slam is a Grand Slam. They're tough. Opponents want to beat you. You hope you show your best tennis."
The Associated Press contributed to this report.