Roger Federer has described his latest remarkable ascent to top of the ATP world rankings as the one that means the most to him.
The 36-year-old will become the oldest man to ever sit at the summit of the men's game on Monday after beating Robin Haase in three sets to reach the semi-finals of the Rotterdam Open, a run that will see him overtake old foe Rafael Nadal.
It is the crowning achievement of a stunning resurgence from the evergreen Federer, who was as low as 17th in the world in January 2017, having missed six months through injury in the previous year.
And Federer, now a four-time world number one, who holds the record for most weeks at the top with 302, believes this achievement outstrips the other times he held the title of best male player on the planet.
"I think reaching number one is one of the biggest, if not the ultimate, achievements in our sport," Federer, who was last number one in November 2012, said on court during a ceremony honouring his rise back to the top.
"Sometimes at the beginning you get there because you're playing so well, later you wrestle it back from someone else who deserves to be there, and when you're older you feel you maybe have to put sometimes double the work in.
"So, this one maybe means the most to me throughout my career, getting to number one and enjoying it at 36, almost 37, years old. It's a dream come true, I can't believe it."
Federer also, somewhat tongue-in-cheek, apologised to Haase, who had to sit through a farewell ceremony for the new number one's friend and retired compatriot Marco Chiudinelli in Basel last year.
"I'd also like to thank Robin for putting up a great fight, he's not been well all week," he added.
"Ironically, he has to go through another ceremony with another Swiss guy, six months ago in Basel he retired my good friend Marco and now he has to watch this, I'm sorry you have to watch these things!"
|Buffon not ready to walk away as Italy look to the future|
|Hamilton breaks records to take pole in Melbourne|
|Curry suffers MCL sprain in first game back from ankle injury|
|Rain ruins day three in Auckland|
|Celtics get another short-handed win, Curry injured again|
|Wozniacki exits as Venus, Konta cruise in Miami|
|Wozniacki stunned by Puig in Miami|
|Mexico 3 Iceland 0: Layun scores brace in friendly win|
|Djokovic struggles continue as Cilic, Dimitrov progress|
|Usain Bolt not ready for top level, says Stoger|
|Ronaldo is a goal – Santos hails Portugal star|
|Pro Bowl TE Bennett announces retirement from NFL|
|Broncos acquire Veldheer from Cardinals for sixth-round pick|
|Dustin Johnson smashes 489-yard drive at Match Play|
|Celtics star Irving to have procedure on knee|
|Giants lose Bumgarner, Samardzija to injuries days before season opener|
|Dybala and Icardi World Cup chances not over yet, says Sampaoli|
|Reed dumps Spieth out, Harman accounts for McIlroy|
|James: Colombia can´t get carried away with France win|
|Italy to wait on Verratti injury|
|Lopetegui happy with Spain showing against ´physically stronger´ Germany|
|Warriors rampant, Weir inspires Edinburgh|
|Messi has had hamstring injury for ´some time´|
|Forward-thinking Southgate makes case for England´s defence|
|McLeish to ring Scotland changes for Hungary clash|
|Rodrigo dedicates Spain goal to Canizares after death of son|
|France were taught a lesson in aggression by Colombia, says Deschamps|
|Late Simmonds penalty breaks Bath hearts|
|Ronaldo up to third on all-time list after Portugal brace|
|Cowboys boost receiving corps with Allen Hurns signing|
|Tigers cling on to win Elland Road thriller, Saints respond at Hull KR|
|Meunier expects PSG will sack Emery|
|Tony Romo finishes last in PGA Tour debut|
|Germany friendly emotionally important for Brazil - Tite|
|France 2 Colombia 3: Quintero completes stunning comeback in Paris|
|Portugal 2 Egypt 1: Late Ronaldo double stuns Salah-inspired Pharaohs|
|No Messi, no Magic – Sampaoli playing a risky game ignoring Dybala|
|Netherlands 0 England 1: Lingard strikes to ruin Koeman´s debut|
|Scotland 0 Costa Rica 1: McLeish suffers defeat in first game back|
|Argentina 2 Italy 0: Banega & Lanzini win it for Messi-less Albiceleste|
|Germany 1 Spain 1: Muller wonderstrike cancels out Rodrigo opener|
|Curry available to make Warriors return against Hawks|
|Paire ousts out-of-sorts Djokovic in Miami|
|Ibrahimovic: If I want to go to the World Cup, I´m there|
|Michael Bennett indicted for allegedly injuring paraplegic woman|
|Svitolina ends Osaka winning run in Miami|
|Australia not ready for World Cup – Van Marwijk|
|Turkey 1 Republic of Ireland 0: Topal strike downs O´Neill´s men|
|Norway 4 Australia 1: Kamara hat-trick spoils Van Marwijk´s Socceroos bow|
|Aguero to miss Argentina friendlies|
|Monaco rubbish reports Rybolovlev will sell club and buy AC Milan|
|Harman sends McIlroy packing in Austin|
|Messi misses Argentina-Italy game|
|Neuer cautious over comeback date despite taking positive steps|
|Lehmann slams ´disgraceful´ Newlands abuse|
|Di Maria predicts ´big change´ at PSG after Champions League failure|
|Everton defender Holgate warned for alleged homophobic tweets|
|Russia 0 Brazil 3: Coutinho on target in routine win|
|Icardi must keep performing to earn Argentina recall, says Zanetti|
|Different place, same Zlatan - Ibrahimovic determined to maintain winning DNA with LA Galaxy|
|Injured Cavendish out of Commonwealth Games|
|Experience the key for Juventus in title race, insists Trezeguet|
|Stanikzai plays through the pain to guide Afghanistan to glory|
|Lyon and Paine frustrate Proteas after Morkel joins 300 club|
|Messi lacks Maradona´s charisma, claims Batistuta|
|Usain Bolt claims he´ll return to Dortmund|
|Trezeguet confident Pogba will shine at the World Cup|
|Ibrahimovic departs Europe with remarkable haul of league titles|
|´Very, very happy´ Lanzini loves West Ham amid transfer talk|
|LA Galaxy confirm Ibrahimovic arrival|