After Roger Federer's rather routine victory over Andy Murray in the Australian Open final on Sunday, where he nabbed his 16th Grand Slam title, there has been increasing chatter along two tracks among tennis writers and fans alike. That is, 1) Federer's latest triumph is more proof that he is the greatest player of all time as he continues to fight back any new competition and is now a threat to actually win the calendar year Slam in 2010; and 2) with Rafael Nadal's injury problems the last nine months, Federer is not being challenged enough and the return of a healthy Nadal cannot come soon enough to restore some semblance of competitive balance on the tour. Both assertions carry legitimacy.

What isn't in question is that though he will be 29 this year - supposedly late middle age for professional tennis players - Federer shows no signs of slowing down, as his wins in three of the last four Slams testifies. And in terms of his place in history he is, at worst, among the top four players of all time; even though there is an increasingly small minority in the tennis universe - yours truly included - that believes that Federer can't be declared the greatest ever while being dominated by Nadal and such Greatest of All Time talk is needless and pointless anyway as it's mighty difficult to compare players across different eras, especially since conditions have changed so much.

For those who believe that a calendar year Grand Slam - that is winning all four majors (Australian, French, Wimbledon and US Open) in the same year - is possible, such talk is misguided. If Federer couldn't do it when he was at his absolute peak from 2004-2007, I'd give it maybe a 10% chance that he could accomplish that near-impossible goal in tennis. The last man to win the calendar year Slam was Rod Laver in 1969 - he also did it in 1962. Steffi Graf was the last woman to do it, in 1988, the year she also won the Olympic gold medal.

Though last year the great Roger finally captured that elusive French title that had bedeviled the Swiss master for so long, it's highly unlikely that he would be able to duplicate that feat again especially if Nadal were healthy. Remember, Federer was just points away from losing to Tommy Haas before mounting an extraordinary comeback from two sets down and was also taken to a fifth set by Juan Martin Del Potro in the semis before routing the completely overmatched Robin Soderling, the man who took out Nadal in the fourth round, in the final. Fed fans do rightfully point out that Roger beat Nadal easily just a couple of weeks before Paris last year and his title wasn't even slightly tarnished by Nadal's absence at Roland Garros.

Federer has used this third act of his career to display a new strength; that of the great escape artist. During those aforementioned years, Federer had to hardly ever rely on comebacks. I don't see how he'd be able to win the true Grand Slam while in a mode of coming from behind at least a match or two per Slam (as he did in Melbourne against Igor Andreev and Nikolay Davydenko).

Speaking of Nadal, there is the odd issue that Federer's continued winning without Nadal creates a dilemma for those who believe that he is the undisputed greatest player of all time. Herein lies the problem - let's say Nadal returns and starts to beat Federer in the Slams again. Will the doubt grow greater for those who dispute the claim that he is the greatest of all time? If Nadal beat Federer again in big matches while Roger still dominated the rest of the field, does that give validity to those who say that this era is still a relatively weak one and Nadal's winning ways against Federer show that he wouldn't be able to win as often if he had more than one true rival?

Or, as the majority who see Federer as the best ever, is Nadal simply the embodiment of that old axiom of the exception that proves the rule? There's obviously no way of knowing.

Now, there are no "should have" or "could have" in sports. That's what makes sports enjoyable to argue about, the results are there on paper, numbers like one's checking account that can't be disputed. So the fact that Nadal is hurt should have no bearing on Federer's legacy. After all, do people doubt Jimmy Connors' return to glory in 1982 following a three year absence in Slam finals? Some claimed back then that the only reason he regained his championship ways was because Bjorn Borg retired, who had utterly dominated Connors in the latter years of their rivalry.

Another case in point is Steffi Graf. The woman who is considered by many to be the best female player of all time dominated from 1988-1990. But starting in 1991 Monica Seles had Graf's number and Graf could only defeat her rival at Wimbledon. But then of course, Seles suffered that horrible stabbing attack and Graf's dominance was immediately reinstated. But it is what it is - you can't lessen the future titles of Graf as she beat who was across the net from her, which is all she could do. Would she have won, say, six or seven fewer Slams if Seles hadn't been stabbed? No one knows.

But one thing is certain now. The tour needs either a healthy Nadal to emerge during his beloved clay season or Del Potro, Novak Djokovic and Murray need to prove to us all that they have the mettle to challenge Federer on a consistent basis, not just an isolated match or two. Who would have thought at the start of 2009 that instead of talking about Federer's final act, we're now hoping for a Nadal comeback? The sport continues to lay out fascinating scenarios for our enjoyment.