Stefanos Tsitsipas was billed as a future star when he turned professional in 2016 and the promising Greek came of age by defeating Roger Federer at the Australian Open.
The 20-year-old produced the performance of his fledgling career to end Federer's reign at Melbourne Park, winning 6-7 (11-13) 7-6 (7-3) 7-5 7-6 (7-5) at Rod Laver Arena on Sunday.
Tsitsipas ended last season by winning the Next Gen ATP Finals title and has wasted no time in breaking new ground in 2019, reaching his first grand slam quarter-final at the expense of the legendary Swiss.
We examine the background of the man of the moment, who will face Roberto Bautista Agut in the last eight.
TENNIS IN HIS BLOOD
Tsitsipas' success at a young age owes much to his parents' connection to tennis.
In an 'ATP Uncovered' video produced in 2017, the youngster said: "My mum used to be a professional tennis player, my dad is a tennis coach - he studied tennis at university.
"They were working as tennis coaches in the resort next to our house. I was hanging around all day, it's how I started actually, I hit my first tennis balls in this club. They introduced me to tennis, basically."
Tsitsipas' father, Apostolos, still coaches him to this day, while the youngster has also benefited from training at the highly regarded Mouratoglou Academy in France.
AGGRESSIVE AND RELENTLESS
An imposing figure at 6ft 4in, Tsitsipas is also a dynamic and agile presence on court.
His forehand is a huge weapon and the exuberance of youth has enabled him to make great progress in a short time.
Countless players are capable of powerful shot-making on the forehand wing, but few can match the versatility of Tsitsipas, whose wide range of strokes must already be the envy of many.
His will to win, battling spirit and sprightly presence on court played a huge part in his magnificent win over Federer.
That coupled with immense natural talent should stand him in good stead to continue to make waves.
MOVING ON UP
Tsitsipas has surged up the world rankings, from 71st in April 2018 to his current position of 15th.
His breakthrough came at last year's Barcelona Open - an ATP 500 event - where he recorded notable wins over Diego Schwartzman, Dominic Thiem and Pablo Carreno Busta on his way to a maiden tour final.
Tsitsipas was trounced by the 'King of Clay' Rafael Nadal in the final, but it was not long before he provided even more compelling evidence of his rare talent.
At the Rogers Cup in Toronto last August, he followed up an opening-round victory over Damir Dzumhur by beating four top-10 opponents in succession - Thiem, Novak Djokovic, Alexander Zverev and Kevin Anderson.
Another final loss to Nadal followed, yet Tsitsipas forced a tie-break in the second set on this occasion and could be hugely proud of a stunning week.
After claiming his first ATP title in Stockholm in October, he ended his season in style in Milan by defeating Alex de Minaur in the Next Gen decider.
MAJOR STRIDES IN MELBOURNE
Tsitsipas was beaten by Federer in straight sets in the Hopman Cup earlier in January but needed two tie-breaks to prevail after failing to break the youngster.
Federer had 12 break points in a thrilling fourth-round contest in the first major of the year, but Tsitsipas saved every one and showed nerves of steel to win two tie-breaks and topple the defending champion.
Tsitsipas demonstrated great maturity by recovering from receiving a pair of time violations after twice failing to beat the serve clock in the first game of the match.
He saved four set points in the second set after losing the first and flashed 62 winners past the 20-time major champion, who had won his previous 17 matches in the first major of the year.
The fearless Tsitsipas looked made for the big occasion, ruthlessly making Federer pay for his missed opportunities as he made major strides.
