Bangladesh, March 24 -- Miami Gardens, Mar 24 (AP/UNB) - The new site for the Miami Open suddenly is missing a lot of star power.

Serena Williams withdrew Saturday, blaming a previously undisclosed left knee injury. Less than two hours later, top-ranked Naomi Osaka lost in the third round to tour veteran Hsieh Su-Wei of Taiwan, 4-6, 7-6 (4), 6-3.

Osaka's departure matched the earliest ever in the tournament by a top-seeded woman and jeopardized her No. 1 ranking, depending on results next week.

"I feel like I've dealt with the stress of people asking me do I have pressure because I have the No. 1 next to my name," Osaka said. "I thought I was doing fine with that, but I guess I'm not."

Roger Federer briefly seemed headed for the exit ...