Andre Agassi believes Roger Federer cannot be called the Greatest of All Time (GOAT) owing to his head-to-head record against Rafael Nadal during their long-standing rivalry in the current era of the game.

The Swiss ace has 19 men's singles Grand Slam titles compared to Nadal's 16 majors, but the Spaniard has dominated proceedings between the two since their first meeting in 2004. Nadal leads Federer 23-15 in their head-to-head record, despite the latter winning their last five encounters.

Novak Djokovic's coach is likely to have made his assessment based on his player's record against Federer and Nadal. The Serb, with 12 Grand Slam titles to his name, has a winning record against both the players, who are considered as the two best of the current era.

Agassi, however, made it clear that his choice was just a personal view as he could very well justify calling Federer the GOAT based on his current record.

Despite refusing to label the 36-year-old Swiss star as the best of all time, the American former world number one is confident that Federer will go down as one of the greats.

The Grand Slam record is one among many in Federer's quiver. He also holds the record for most consecutive weeks as the number one, he has won the Wimbledon a record eight times, the season-ending ATP Finals a record six times and is second in the all-time list of overall titles won – Jimmy Connors holds the record with 109 titles. He is also top in the popularity votes, having won the ATP Fans' Favourite award for a 15th straight year in 2017.

"A player cannot be considered the best of all time if he has been beaten so many times by a rival," Agassi said, as quoted by the Metro.

"My choice is purely arbitrary. I could just as easily defend the opposite view and prove to you that Federer is the best. The debate has no rational basis, it comes down to 'and if ...' It's just a debate," he added.

"Federer is unique. In all: greatness, accuracy, ease. He plays tennis so differently from others," the American said, praising Federer.

"Federer gives off that feeling of control, of having a solution for every problem. We cannot deny that Federer will mark the sport forever."

Roger Federer
Roger Federer and Rafael Nadal have faced each other 38 times so far, with their first meeting coming in 2004 Getty