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!"
|Men´s tennis will have to ´wake up´ after Federer and Nadal, says King|
|Tennis star Djokovic backs VAR despite Serbia controversy|
|Socceroos have deserved more at World Cup – Skoko|
|Dodgers top Mets in Kershaw´s return from DL|
|MLS Review: Red Bulls end Dallas´ unbeaten run, Sporting stage comeback|
|Hierro: This Spain team similar to 2010 World Cup champions|
|Dowrich, Holder lead Windies fightback after poor start|
|With Neymar back, Brazil are World Cup favourites – Lugano|
|Alba: I don´t understand the criticism of Messi|
|He has sacrificed a lot – Stuani praises Suarez|
|Manning says Brees deserves to break his record for career passing yards|
|Hornets want Walker to play entire career with Charlotte|
|Avalanche sign Grubauer to three-year extension|
|Argentina struggles down to team, not just Messi – Hierro|
|Casey leads Travelers by four after firing 62|
|Scotland run riot in Argentina as Hourcade tenure ends in defeat|
|Germany´s Rudy in doubt for South Korea clash|
|England produce storming fightback to beat New Zealand|
|Shaqiri, Xhaka facing disciplinary action over goal celebration|
|Kvitova takes WTA lead for wins by easing into Birmingham final|
|Jones: England back on road to being world´s best|
|Germany survive in Sochi but questions remain|
|Germany 2 Sweden 1: Late Kroos winner brings Low´s men back from the brink|
|Perisic dreaming of matching Croatia´s France 98 heroes|
|Veron questions Sampaoli for leaving Icardi out|
|Southgate won´t blame injured Alli for playing through pain barrier|
|Travelers Championship: Course invader drives Rory McIlroy and crowd nuts|
|Saul tells Atletico to renew Oblak deal after Griezmann´s new contract|
|Course invader sends McIlroy & crowd nuts at Travelers Championship|
|Saudi Arabia v Egypt: El Hadary eyes history in dead rubber|
|Referee declines Cheika invite after Australia´s series loss to Ireland|
|Griezmann, Mbappe can eclipse Henry, claims Trezeguet|
|Nawalka hopeful of Glik return against Colombia|
|Mexico outsmart South Korea to join Croatia as unheralded World Cup threats|
|´No drama´ for Southgate after England team sheet leak|
|Hend caught by five in Pulheim as Bjerregaard goes low|
|´Little Pea´ Hernandez hits big Mexico milestone in World Cup win|
|Modric and Rakitic the best midfield in Russia - Corluka|
|Cipriani and Farrell ease pressure on Jones as England avoid SA whitewash|
|South Korea 1 Mexico 2: Hernandez nets landmark goal as last 16 beckons|
|Ozil and Khedira axed by Germany|
|Djokovic plans to use two rackets against Cilic after reaching Queen´s final|
|World Cup of penalties? Russia surpasses Brazil after VAR introduction|
|Neymar ´fully recovered´ but Brazil coach Tite has thigh injury|
|Hansen claims France ´clutching at straws´ after another referee controversy|
|Douglas Costa, Danilo out of Brazil´s Serbia clash|
|Hamilton claims 75th pole as Mercedes dominate in France|
|´Mentally strong´ Salah will overcome World Cup disappointment, says Mane|
|Pekerman contemplating unleashing James and Quintero together|
|Schmidt hopes Australia furnace will produce Ireland diamonds|
|I´m missing practice, but it´s OK - Federer ready for Coric|
|Spain v Morocco: Alba makes case for the defence|
|Team-man Lukaku firmly in the race for individual prize|
|Belgium 5 Tunisia 2: Lukaku and Hazard shine as Red Devils run riot|
|Leaked England team gives Panama no advantage, insists Gomez|
|Mane and Senegal holding no fear for Japan|
|Murray to meet Wawrinka at Eastbourne|
|Nigeria goalkeeper Ikeme in remission after year-long cancer battle|
|Lukaku breaks Belgium record against Tunisia|
|Iran v Portugal: Team Melli bullish over qualification chances|
|Mauresmo to be France´s first female Davis Cup captain|
|Maradona angry at Argentina World Cup performances|
|Ireland cap stunning season with series win over Wallabies|
|Uruguay v Russia: Selection posers for already-qualified pair|
|Federer scraps his way to yet another Halle final|
|Lunin rejected ´3,000 offers´ to join Real Madrid|
|On your bike! Iceland physio sent home after cycling accident|
|Not just Real Madrid interested in Fekir, says Aulas|
|France frustrated by officials again as All Blacks complete sweep in style|
|Jose Enrique reveals brain tumour surgery|