After all, 20-times Grand Slam champion Roger Federer was also a relatively late bloomer.
In his record 12th French Open quarterfinal, Novak Djokovic will face a man he knows well, even if the rest of the world does not.
Zverev was taken to five sets by Dusan Lajovic in the second round and saved match point against Damir Dzumhur in the third round. Dzumhur held serve routinely, but was taken to deuce before taking the tenth game and set 6-4.
While Zverev, whose brother Mischa is also playing in the third round, reached the last 16 at Wimbledon past year, he has largely failed to live up to his world number three ranking in Grand Slams so far.
Not everyone was winning this week, though - especially one of the ball boys.
She dropped the first set against American Alison Riske 6-2, before recovering for a comfortable victory, losing just two games for the rest of the match.
While Zverev has already made a name for himself on the tennis tour by climbing to third in the rankings and amassing three Masters titles by the age of 21 - multiple Masters victories in the last decade have usually been reserved for the "Big Four" - he has yet to reach a grand slam quarterfinal.
She trailed Destanee Aiava 5-2 within the first set of her first match in Melbourne and saved three match factors within the third spherical towards Lauren Davis.
Frequently touted as a future world No.1, the 21-year-old's grand slam performance remains checkered, having never advanced past the fourth round in 11 tries.
Keys next faces unseeded Yulia Putintseva of Kazakhstan, who beat 26th-seeded Czech Barbora Strycova 6-4, 6-3.
"When he made me run, he was actually dictating the rallies", said Goffin, whose right elbow was looked at by a trainer during the match, "so it was hard for me to have the upper hand".
The 2016 champion beat 13th-seeded Roberto Bautista Agut of Spain 6-4, 6-7 (6), 7-6 (4), 6-2, in a near four-hour match too sluggish for Djokovic's liking.
His victory is unlikely to be welcomed by fiery Italian Fabio Fognini, who launched into a tirade against supposed preferential treatment for the ATP's "NextGen" players at the French Open.
"I am pretty exhausted but happy to have finally got the victory against a clay court specialist", the Serb said after the match. Japan's Kei Nishikori rolled over French star Gilles Simon 6/3; 6/1; 6/3, while America's Madison Keys powered her way to a 6/1; 7/6 (7) defeat of Japan's Naomi Osaka.
They were playing their match later Sunday on Court Suzanne Lenglen.
Mihaela Buzarnescu, making her French Open main draw debut, pulled off a 6-3 7-5 upset win over fourth seed Ukrainian Elina Svitolina. Serving for the match, Zverez was up 30-0 but dropped the next two points for 30-all. But Bautista Agut fought back and claimed the break back in the seventh game. He then held serve throughout to wrap it up on his second match point when Nishikori sent a forehand long under the eyes of Nadal.
He seems more equipped for the former now than ever.
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