João Fonseca, 18, upsets No. 9 seed in Australian Open debut - ESPN

MELBOURNE, Australia — João Fonseca definitively introduced himself to the world as the latest teen sensation in men's tennis on Tuesday night, upsetting No. 9 seed Andrey Rublev 7-6 (1), 6-3, 7-6 (5) in the first round of the Australian Open.

It was quite a debut in the main draw of a Grand Slam tournament for the 18-year-old Brazilian, who is currently ranked 112th and made it into the bracket at Melbourne Park by winning three matches in qualifying rounds last week.

The victory over 10-time major quarterfinalist Rublev, who is 27, lasted just under 2 1/2 hours and stretched Fonseca's current unbeaten run to 14 matches. That includes taking the title last month in Saudi Arabia at the Next Gen ATP Finals for top players who are under 21, and another trophy this month at a lower-tier Challenger tournament in Canberra.

Those within tennis have been keeping tabs on 2023 U.S. Open junior boys' champion Fonseca for a bit, intrigued by his big serve, booming groundstrokes and cool demeanor. All of those qualities, and more, were on display against Rublev in Margaret Court Arena, the second-biggest stage in Melbourne.

Fonseca got to match point with a backhand winner that he celebrated by raising his right index finger in a No. 1 gesture and nodding his head. Then he ended it with a down-the-line forehand, spreading his arms wide and tossing his head back.

«I mean, not bad,» were Fonseca's first words during his on-court interview afterward.

That drew a smile from him and supportive laughter from the stands, where there were plenty of fans sporting his home country's green-yellow-and-blue flag.

«I just enjoyed every moment in this court, this amazing court,» he continued. «My first time playing in a huuuuge stadium» — dragging