Roger Federer has broken Jimmy Connors' 30-year-old record to become the longest reigning world number one.
Federer returns this week for the first time since the Australian Open
The 25-year-old Swiss ovetakes Connors as the first man to hold the top position for 161 consecutive weeks.
"I've been looking forward to this day and I'm very excited," he said. "It is definitely one of the biggest records I've broken so far in my career."
Federer returns after four weeks off at the Dubai Open this week, along with world number two Rafael Nadal.
I remember when my game was still up in the air
His reign as world number one began on 4 February, 2004, and such is his lead in the rankings he is certain to remain number one for months to come.
Connors' unbeaten run at the top of the rankings came between July 1974 and August 1977.
"He's still got the record for most titles (109 to Federer's 46) which I don't think will ever be eclipsed," said Federer. "He's one of the all-time great players.
"He played for such a long time which allowed him to get so many titles, but to stay fit through all that time with his intensity and everything, it's quite remarkable.
"We know players today who are intense - Hewitt and Nadal. Can you imagine them playing until 40 years old? It's almost impossible but Jimmy did that."
Federer added: "I remember when my game was still up in the air. On any given day I could play very well, but on my off days I would be very vulnerable.
"My baseline game was OK but not as consistent as I was hoping for. That's what I've been able to improve.
"Fitness-wise as well, I had problems. I was always hoping not to go five sets, whereas now I don't mind it. So I've really come a long way."
Speaking to Five Live, three-time Wimbledon champion and former number one John McEnroe said: "It's remarkable.
"Not the fact that he's so good, but the combination of consistency, his fitness levels and desire and absolute will to win every single week."