When Novak Djokovic and Carlos Alcaraz lost to Alexei Popyrin and Botic Van de Zandschulp respectively at the US Open last year, the tennis world was shocked.
Defeating two of the biggest names in men’s tennis would surely be a huge confidence boost for the two lower-ranked players.
Yet both were eliminated in their very next rounds; the fact that neither player was able to back up their wins was perhaps unsurprising.
MORE: All the results from AO 2025
Djokovic and Alcaraz had just played in the Wimbledon final and the Paris 2024 Olympic Games gold medal match, with Alcaraz also having taken the title at Roland Garros in May of that year.
Playing so much tennis, let alone changing surfaces from clay to grass, back to clay and then to hard court for the US Open was always going to take its toll on both, mentally and physically.
So is it really so hard to back up an upset?
At this year’s Australian Open, several names have done just this, including two American young guns.
Teenager Learner Tien shocked fourth seed Daniil Medvedev in the second round and then followed it up with a win over tricky Frenchman Corentin Moutet.
Twenty-year-old Alex Michelsen notched up upsets of his own, against 11th seed Stefanos Tsitsipas in the first round and 19th seed Karen Khachanov in the third.
Both players have taken it in their stride, with Tien addressing this concern after his win over Moutet.
“I had that in mind, that inevitable drop-off after a big win or a good match,” he said.
“I gave myself a little bit of time just to process the match and take it all in. After that, it was on to the next match and focusing on my match I had today (against Moutet).
“I was able to do it pretty well and put that match behind me, but still taking some confidence from the win.”
As well as putting in the “hard yards this off-season”, good friend Michelsen says things have just started to click at AO 2025, particularly in key moments.
“I've played the pressure points pretty well. Tiebreak, 7-5, then I hit two winners from 5-all. I don't know where it came from. It just kind of happened.”
And it’s not only the young guns that are backing up their upsets.
As the second-oldest man to make it to the round of 16 at the Australian Open, Frenchman Gael Monfils has already made his mark on the tournament.
Having defeated 30th seed and fellow countryman Giovanni Mpetshi Perricard in a truly thrilling five-set encounter, ‘La Monf’ saved his best performance for 4th seed Taylor Fritz, rolling back the years and notching up his first top-five win at a Grand Slam since 2008.
As a husband and a father now, the 38-year-old, however, has different priorities.
“To be honest with you, is not even a dream to win the tournament. My dream is to be old and with a lot of kids and healthy,” Monfils reflects.
With age comes experience and the Frenchman believes this adds a new element to his game.
“With my form now, I have more experience, so I can adjust myself. As you say, my game plan was a bit different. I knew how to slow down, how to change rhythm a little bit.”
Should he defeat the big serving American and 21st seed, Ben Shelton on Monday, Monfils will continue an incredible run, making the quarterfinals for the first time since 2022.
Along with Monfils, Tien and Michelsen are both still in the running at AO 2025 for the time being.
In the women's draw, world No.55 Olga Danilovic was impressive in her win over 7th seed and reigning US Open finalist Jessica Pegula. This followed her first-round victory over 25th seed Liudmila Samsonova, before she fell to No.11 seed Paula Badosa.
Belinda Bencic came close to pulling off two incredible upsets, going down to third seeded American Coco Gauff in three sets having defeated 16th seed Jelena Ostapenko and Dutchwoman Suzan Lamens before advancing to the fourth round following the retirement of four-time Grand Slam winner Naomi Osaka.
Veronika Kudermetova also had a couple of solid wins with victories over seeds Katie Boulter and Brazilian Beatriz Haddad Maia before losing to 28th seed Elina Svitolina.
So, what explains these performances – with multiple players backing up an upset at AO 2025?
It is likely the confidence of youth for some, and the wisdom of experience for others, but sometimes things just click for players with less pressure and expectation.