After passing Pete Sampras' record by winning his 15th grand slam tennis title, the question is being asked about whether Roger Federer can now be considered the greatest tennis player of all time.
There are two serious contenders for this title - not considering the likes of John McEnroe or Bjorn Borg, who were not as consistent over as long a period. Sampras and Rod Laver are the others who can be placed alongside Federer in this conversation. Federer now has 15 grand slams among 60 career titles in ATP tour events, compared to Sampras with 14 slams and 64 titles and Laver with 11 slams and 27 ATP titles.
The complication with going on pure statistics is that Laver spent much of the glory years of his career outside the ATP tour, as his run coincided with the advent of the open era. He played as an amateur until 1962, winning six of his slams including a Grand Slam in the calendar year of 1962 before turning professional, which disqualified him from the still-amateur ATP tour. It was not until 1968 that the open era began and he was allowed to return to the ATP tour, after which he completed a second calendar year Grand Slam in 1969 as a professional at the age of 31.
There are arguments either way. Three of the four slam tournaments that Laver played in were on grass, whereas Sampras and Federer have had to win on synthetic surfaces as well. On the other hand, Laver is the only one of the three to have won more than one French Open. You could argue that Sampras may have had the greatest array of opponents facing him, with the likes of Ivan Lendl and Andre Agassi where Laver's main rival was Ken Rosewall and Federer has struggled mightily with his nemesis in Rafael Nadal.
In fact, it is Nadal who stands in the way of Federer's claims. Federer did not have to play the Spaniard in either of the last two Slams and it was Nadal who had beaten him in the final of three of the previous four slam tournaments. Federer's 7-13 record against Nadal, including 2-6 in slams, is the greatest flaw in his record.
Personally, being an Aussie, I realise I am biased in thinking Laver would have the wood over the American and the Swiss champions. However, the six-year hole in his ATP record is only a potential for slam tournaments so we will never know if he could have reached 20 or more. Federer could still get somewhere near there... but only if Nadal stays injured.