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!"
|Salah can push on to Messi´s level - Robertson|
|BREAKING NEWS: Rabada free to play in rest of South Africa-Australia series|
|F1 2018: Halo splits opinion ahead of Australia debut|
|Iniesta better than last year – Lopetegui|
|Federer yet to decide on clay-court season|
|Okon quits as Mariners head coach|
|LeBron triple-double powers Cavs past Bucks as Love returns|
|Lopetegui: Morata must earn World Cup spot|
|Ronaldo has asked about China – Scolari|
|Ebron signs two-year deal with Colts|
|Spieth, Reed to do battle in Match Play|
|Rangers´ Perez slaughtered, ate bull that caused broken elbow|
|Bills improve offensive line with Bodine, Newhouse|
|Braves phenom Acuna to start season in minors|
|Chargers add Pouncey on two-year deal|
|Ronaldo: I always show I´m the best|
|Joshua would love another Whyte tear-up, says Hearn|
|Manchester United not in Jorginho talks, says Napoli star´s agent|
|Hazard will not be false nine for Belgium, says Martinez|
|Bancroft confident on Starc and Marsh fitness|
|Mayweather to apply for MMA licence|
|Martial agent will not guarantee Manchester United stay|
|Del Potro and Djokovic on early collision course at Miami Open|
|Siemian swaps Broncos for Vikings|
|Broad chomping at the bit to bowl at Black Caps´ Taylor|
|Ronaldo slams ´fake news´ amid latest tax case claims|
|Van Dijk and Gundogan expect tough City-Liverpool tie|
|VAR to be introduced in Eredivisie|
|Di Biagio sees bright Italy future with Cutrone and Chiesa|
|Koeman won´t rule out Van Persie Netherlands return|
|I ate badly for years – how Messi solved his vomiting problem|
|England and Bath´s Watson out for the season|
|McLaren issues ´have been addressed´ ahead of F1 season opener|
|Tuchel feels he would still be at Dortmund without bomb attack|
|Pogba shows off new haircut as Ben Yedder trolls Man United star|
|Pogba cannot be happy but must focus on France, says Deschamps|
|Samuels slogs Windies closer to World Cup qualification|
|Having Rabada in third Test massive - Elgar|
|Cavs coach Lue steps away from job due to health reasons|
|Debuchy disappointed to be left out of latest France squad|
|Barton rejects England´s World Cup chances|
|Hamilton can become greatest F1 driver in history - Kovalainen|
|Sevilla coach Montella interested in Italy job|
|Football brain lacking, poor attitude and fourth choice – The Mourinho-Shaw saga at Manchester Unite|
|I´ve had enough - Pietersen confirms retirement|
|UEFA charges Marseille and Lyon for Europa League trouble|
|Broad ready to do damage in New Zealand series|
|Injured Chiellini out of Italy squad|
|Toulon-bound Webb out for rest of season|
|Buffon cites Astori among reasons for Italy return|
|Welbeck faces no action over alleged dive against Milan|
|Charnley switches back to league to join Warrington|
|Barcelona? I´m staying with PSG, insists Marco Verratti|
|Bastian Schweinsteiger & Ana Ivanovic announce birth of son|
|The numbers behind Cristiano Ronaldo´s 50 hat-tricks|
|Woods relishing end to frustrating Augusta absence|
|Consistency the only thing stopping me from being the best, claims Depay|
|Guardiola second to none tactially, says Man City midfielder Gundogan|
|McIlroy: Bay Hill win a huge confidence boost for Masters|
|F1 2018 Pre-Season Report: Mercedes|
|F1 2018: The best Opta facts ahead of the new season|
|Liverpool captain Henderson ponders Salah and Suarez comparison|
|Messi worried by the uncertainty retirement brings|
|F1 2018 Pre-Season Report: Ferrari|
|Hunt handed ban and fine but cleared to return|
|Rants, criticism a familiar story – Is Mourinho set for Man United exit?|
|Guptill added to Black Caps squad|
|Thunder end Raptors´ streak, Davis stars|
|Stars goalie Bishop expected to miss at least two weeks|
|Messi desperate for World Cup success|