Emma Raducanu knows full well what it is like to be a little-known qualifier upsetting the odds at a Grand Slam tournament.
On Sunday, the boot will be on the other foot at Wimbledon.
The 21-year-old Briton famously won the US Open as a teenager qualifier three years ago, creating one of the most stunning shocks in sporting history.
Now Raducanu faces New Zealand qualifier Lulu Sun, a 23-year-old who had never played in the Wimbledon main draw until this year.
The pair meet in the fourth round at around 17:00 BST on Centre Court.
“Qualifiers are dangerous,” said Raducanu, who has not dropped a set in her opening three victories.
“She’s had three extra matches here at Wimbledon and she is not to be underestimated.”
Sun, ranked 123rd in the world, created one of the shocks of the tournament by beating Chinese eighth seed Zheng Qinwen in her first-round match.
She is the first woman representing New Zealand to reach the fourth round of Wimbledon in the Open era.
“The preparation doesn’t change I don’t think, you just take it opponent by opponent,” said Raducanu, who is ranked 135th in the world after injury issues last year.
“I’m expecting her to be really dangerous and come out swinging so it’s going to be a really tough match.”
Raducanu missed last year’s Wimbledon after having surgery on both of her wrists and has needed to be patient on her return to the WTA Tour this year.
Difficult decisions have also needed to be made.
On Saturday, she made the “very difficult” move to pull out of her mixed doubles partnership with Andy Murray – whose Wimbledon career is now over – because of stiffness in her wrist.
Raducanu has been cautious in her scheduling this year and opted to miss the clay-court French Open in order to ensure she was in peak condition for the British grass-court season.
The move has been fully justified.
After encouraging runs in Nottingham and Eastbourne, Raducanu has played some of her best tennis this week since winning the US Open.
“Honestly, I’m just obsessed with tennis right now,” said Raducanu.
“It’s all I want to do and all I want to think about.”
Raducanu needed to come through a first-set tie-break against Mexican lucky loser Renata Zarazua in round one, but has dropped just 11 games since after commanding wins over Belgium’s Elise Mertens and Greek ninth seed Maria Sakkari.
The excitement among the British fans at the All England Club has been further fuelled by Raducanu’s section of the draw opening up.
If the former British number one beats Sun, another unseeded opponent – Spanish former world number two Paula Badosa or Croatia’s Donna Vekic – waits in the quarter-finals.
“I just love playing on the big stages so much,” said Raducanu.
“It’s my favourite thing in the world, it’s the reason I play tennis, to play on these big courts and these big matches.
“It’s really special, you don’t get these opportunities often in life.
“When I look back later in my career, when I get much older and have retired, I want to be able to tell myself I savoured every moment.
“So I play each point as if it’s my last.”
Defending men’s champion Carlos Alcaraz opens the day’s play on Centre Court when he faces French 16th seed Ugo Humbert in the fourth round.
After Raducanu’s match, there is an all-American clash between second seed Coco Gauff and 19th seed Emma Navarro.
On Court One, Italian seventh seed Jasmine Paolini – who reached the French Open final last month – takes on American 12th seed Madison Keys.
One of that women’s quartet is a potential semi-final opponent for Raducanu should she get that far.
Italian men’s world number one Jannik Sinner, who is aiming for his first Wimbledon title, plays big-serving Ben Shelton of the United States.
That match is followed on the second show court by Russian fifth seed Daniil Medvedev taking on Bulgarian 10th seed Grigor Dimitrov.