Jannik Sinner had just become the youngest men’s singles finalist at the Australian Open since the man he had beaten, Novak Djokovic (2008). Yet, you couldn’t tell looking at the young Italian.

Sinner celebrated the greatest victory of his career by simply raising both his arms and flashing a smile. No exaggerated antics, no overpowering emotions. “My tournament is not over yet,” Sinner would say later.

Cut to six months ago when Carlos Alcaraz’s tournament was indeed over at Wimbledon, the Spaniard slumped to the worn-out greens of Centre Court with emotions bubbling over.

Common between these contrasting reactions by two fine young talents in men’s tennis was the statistical GOAT (greatest of all time) standing across the net. The only defeat Djokovic suffered in a Grand Slam last year was inflicted by the 20-year-old Alcaraz. The only defeat Djokovic suffered in the semi-finals of Australian Open ever was inflicted by the 22-year-old Sinner.

In six months and two of the previous three Slams, a couple of twenty-somethings have managed to dislodge a thirty-something 24-time major champion who had refused to budge for the longest time on the biggest stages of tennis.

Talk of the proverbial change of guard in the men’s game has been going on for as long as people thought the Big Three (the fine club of Djokovic, Rafael Nadal and Roger Federer) would no longer be the big force it once was, especially when the rising prowess of Alexander Zverev, Daniil Medvedev and Stefanos Tsitsipas was in motion. However, what stands out now is that Alcaraz and Sinner — both are younger than the guys above in their mid-twenties — have stalled Djokovic in Slams and in the latter stages where the stakes multiply.

That has rarely happened over the last few years, and quite sporadically. Other than Tsitsipas beating Nadal in the quarter-finals of the 2021 Australian Open and Medvedev winning his first Slam at the expense of Djokovic’s Calendar Slam history bid, the old guard had been largely unruffled in Slams. Now Sinner, the only man to beat Djokovic in the Australian Open semi-finals, and Alcaraz, the first man to beat Djokovic in the Wimbledon final in a decade, have begun hurling the new guard’s flag where it counts the most.

It helps the latest bunch that two from the Big Three have been largely away over the last few years (Federer with his retirement and Nadal with his injuries), leaving Djokovic to do all the standing and stalling. It also helps that they’ve frequently beaten him on the tour.

The Djokovic-Alcaraz rivalry may have been the flavour of the 2023 season but Sinner too whipped up fruitful results in his four battles against the Serb last year, winning twice. Sinner’s win-loss record against Djokovic is a close 3-4. Alcaraz’s is 2-3, and so is Holger Rune’s, another 20-year-old from whom big things are expected.

All those wins add up in the belief factor when they front up with Djokovic in a Slam.

“Each one of us is a different player. Also mentally and in the attitude on court, everyone is different. But what we have in common is that we believe in ourselves, and this helps a lot. Because in tennis when you believe, it’s a huge amount already,” Sinner said of the trio.

Djokovic, who has translated belief into 24 Slam titles, also senses that. For him, the biggest aspect of growth in Sinner — whom he beat at the 2022 and 2023 Wimbledon in hard-fought contests — has been in his mindset shift in matches that matter more.

“He was always smacking the ball hard, plays very quick, loves to be aggressive. I think his serve improved a lot. And the mental part,” Djokovic said of Sinner. “He was always very calm and composed on the court, but he struggled maybe to win the big matches in the big moments. But now it’s coming together for him.”

Not that it’s falling apart for Djokovic, yet. At 36, in a tournament where he wasn’t at his best physically and health wise, he has “not played upto my standard”. “But it doesn’t necessarily mean it’s the beginning of the end,” he added.

A Sinner-Medvedev final though, the first Australian Open title clash not featuring a member of the Big Three since 2005, means the new guard is increasingly making its presence felt in Grand Slams.