Game of frustration: Roger Federer and Andy Roddick after the 2004 Wimbledon final.

PARIS: Regarded as one of the greatest players of all time, Roger Federer on Sunday celebrates his 40th birthday with his career at a crossroads.

AFP Sport looks at some of the plaudits he has received during his 23 years in the sport where he has won 20 Grand Slam titles and 103 trophies in all:

"I threw the kitchen sink at him but he went to the bathroom and got his tub."

-- Andy Roddick on losing the 2004 Wimbledon final to Federer.

"In the modern game, you're either a clay court specialist, a grass court specialist or a hard court specialist … or you're Roger Federer."

- Former US great Jimmy Connors

"I feel that this rivalry is not only in the tennis world. People from outside of our world talk about it and that's good for our sport."

- Rafael Nadal at the 2017 Australian Open

"He hits shots that other guys don't hit. You want to go over and give him a high five sometimes."

- Sam Querrey after Federer hit a 'tweener' in their clash at Wimbledon in 2015.

"Roger can produce tennis shots that should be declared illegal."