Holger Rune says it will be "cool" to face Carlos Alcaraz, who he played doubles with as a 13-year-old, on a day of reunions and rematches at Wimbledon.
In the women's quarter-finals, Ons Jabeur meets defending champion Elena Rybakina in a repeat of the 2022 final.
That is followed by a contest between two 20-year-olds - Denmark's Rune and Spanish world number one Alcaraz.
"I remember when we were 12 or 11 years old, that is the first time I saw him," Alcaraz said.
"I talked with him a little bit. I remember really clearly."
A clip of the pair, then fresh-faced 13-year-olds, playing doubles together at a junior tournament in France has been widely shared on social media in recent days.
Rune, who is bidding to reach his first Grand Slam semi-final, said: "He's always been a very passionate player on the court, I would say, with a lot of energy.
"A big forehand, also in juniors. I think he's the same, just so much better now."
The match on Centre Court will be the first quarter-final between two players under the age of 21 in the Open era at Wimbledon.
"For me it's cool, for him it's also cool, I guess," Rune said. "To be able to play a quarter-final against a player that is your same age, at the top of the ranking, feels amazing."
Alcaraz is viewed as the most likely challenger to Novak Djokovic in the men's singles, having won his first Grand Slam at the US Open last year and found his feet on grass by winning Queen's in the run-up to this year's Wimbledon.
World number six Rune is more animated than Alcaraz on court and there are suggestions his behaviour is not popular among his fellow players.
"When you see him play, he reminds me a little bit of Lleyton Hewitt back in the day," former Grand Slam champion Kim Clijsters told BBC Radio 5 Live. "He wasn't liked much either, but off the court they are nice people.
"There's definitely a history between the two that can maybe have an impact on the mindset of Alcaraz a little bit. He's supposed to beat him, he's supposed to be better."
'I've learned a lot from last year' - Jabeur
Jabeur went into last year's women's final as the higher-ranked player but was overpowered by Kazakh Rybakina who came from a set down to win 3-6 6-2 6-2.
The Tunisian said she will "definitely learn" from last year's defeat.
"I think the first one or two weeks I thought about it a lot," she said. "It was very painful. The good thing about it is I know I gave it everything."
The women's singles draw opened up on Tuesday when Elina Svitolina knocked out world number one Iga Swiatek. That leaves Rybakina and second seed Aryna Sabalenka as the favourites.
Belarusian Sabalenka, who won the Australian Open earlier this year, plays American Madison Keys in the opening match on Court One on Wednesday.
Keys is contesting her second Wimbledon quarter-final - eight years after her first.
That match is followed by men's third seed Daniil Medvedev against surprise package Chris Eubanks.
The American world number 43 has reached his first Grand Slam quarter-final on his debut at Wimbledon.
Elsewhere, there is British interest in the women's doubles with Naiktha Bains and Maia Lumsden - the first British pair in the quarter-finals since 1983 - and in the men's event.
Jamie Murray and New Zealander Michael Venus, plus Murray's fellow Briton Neal Skupski and his Dutch partner Wesley Koolhof, play their quarter-finals.
The wheelchair events, featuring Gordon Reid, Alfie Hewett, Andy Lapthorne, Lucy Shuker and Gregory Slade, also start on Wednesday.
