Joao Fonseca announced himself on the grand slam stage at the Australian Open by upsetting Andrey Rublev on his main draw debut at Melbourne Park.

Fonseca, who won the Next Gen ATP Finals last month, carried on his year-end form by dispatching Rublev in straight sets, emerging a 7-6 (6-1) 6-3 7-6 (7-5) victor on Tuesday.

The pair traded blows in the opening set, with the early advantage coming down to a decider, with the Brazilian feeding off the crowd's energy to edge into a surprise lead.

Fonseca then raced into a 3-0 lead in the second, breaking Rublev in the second game before edging closer to a monumental victory with two love games on serve.

Rublev, however, responded well, earning an early break, though his advantage was immediately diminished with Fonseca bouncing back over the next two games.

And world number nine Rublev failed to recover from that setback, with Fonseca seeing out the decider despite having built up a 4-0 lead before his opponent rallied back.

The Brazilian's reward is a second-round meeting against Lorenzo Sonego after the Italian beat veteran Stan Wawrinka 6-4 5-7 7-5 7-5 earlier on Tuesday.

Data Debrief: Teenage kicks

Having become the first South American teenager to qualify for a men’s singles main draw at a grand slam event since Juan Martin del Potro (US Open 2006), Fonseca showcased why he is not a player to be overlooked at the tournament.

He became only the second teenager to defeat an ATP top 10 opponent in their maiden grand slam match, after Mario Ancic beat Roger Federer at Wimbledon in 2002.

Fonseca also became the first teenager to defeat an ATP top 10 opponent in straight sets at a grand slam event since Rublev did so himself against Grigor Dimitrov at the US Open in 2017.

Rublev, meanwhile, lost in the first round for the first time at the Australian Open since 2019. He is the second Top 10 player to exit at this year's event after Dimitrov's retirement.