The unseeded Azarenka is a three-time Miami Open champion.
After a one-day delay because of rain, the tournament started Wednesday at the Miami Dolphins’ complex. The 13,800-seat stadium was mostly empty for the opening match, but bigger crowds are expected when seeded players begin taking the court. They have first-round byes.
“Standing here in this stadium right now, you see the magnitude, what kind of an arena this is,” Federer said. “I think it’s a big, massive moment in our sport.”