(CNN) - Roger Federer wasn't very happy when relayed John McEnroe's comments that his loss to 20-year-old Stefanos Tsitsipas in the fourth round at the Australian Open was a "changing of the guard" moment.
It is easy to utter such a phrase given that Federer is 37 and hasn't made a grand slam semifinal since last year's Australian Open.
But McEnroe -- who is prone to headline grabbing quotes -- does have a point or at least as it relates to the perspective on Federer.
As much of a talent as Tsitsipas is, tennis history tells us that can't-miss prospects can wane into solid pros who never quite hit the heights expected of them. Tsitsipas, though, does seem to have it all. Power, precision, variety, desire -- and a modest swagger.
But back to the legendary Swiss.
Federer's last three losses at grand slams have boggled, because of just how good he has been for nearly two decades in clutch moments.
Indeed when he said he "created a monster" here in 2008 after a semifinal defeat to Novak Djokovic -- the point being that all his wins led people to believe he was untouchable -- Federer was correct.
More than 10 years later, he is still playing at an incredibly high level, giving the man of the moment Djokovic one of his toughest matches in 2018 in a phase when the Serb seemed untouchable himself, and finishing the season in the top three.
The issue for Federer is that grand slams, as he knows, are the best of five sets and the edge he held is ever so slightly dissipating. Even if it is a 1% shift, at this level it is the difference between a fourth round or potentially a semifinal: Movement, explosiveness off the ground and maybe even Federer's own confidence.
Federer held a 4-0 record -- no sets lost -- against the big-serving Kevin Anderson prior to losing their quarterfinal after holding a match point at Wimbledon.
Federer later revealed he suffered from a hand issue yet he had only ever experienced one loss at Wimbledon from two sets up.
And he said he wasn't hurt when falling to the Australian John Millman in the fourth round of the US Open.
It wasn't the killer instinct that lacked then, but rather the steamy conditions got to Federer. That seemed like an unprecedented occurrence for the man who was always unflappable no matter the weather.
Never in recent memory had the great man suffered like that physically, barring an injury.
And then against Tsitsipas, Federer unbelievably went 0-for-12 on break points. At ATP and grand slam level, at first glance, it was believed to be the only time in Federer's career he manufactured double digits in break points without taking at least one of those chances.
All three losses came when Federer won the first set.
He had been 87-2 in Melbourne when grabbing the first set, beaten only by two players who were already grand slam champions, Rafael Nadal and Marat Safin.
First time in a while
And the last time he went three straight majors without making a semifinal? In 2013.
Those numbers certainly tell us Federer isn't the player he was as recently as 2017, when he claimed two of the three majors he contested after coming back from a knee problem.
If he intends to keep on going -- and there was nothing to suggest that wasn't the case Sunday when he spoke to reporters -- not for the first time he will have to ponder what adjustments to make.
He has brought in coaches in the past and the results have been an improved one-handed backhand and the SABR tactic -- coming to the net on service returns after taking the ball early.
It would be highly surprising if Federer dispenses with his coach Ivan Ljubicic but would he add an extra voice?
Likely the first big decision Federer must make is whether he will, as murmurings suggest, play a full clay-court swing for the first time since 2015.
With this unexpected start to his season, featuring in the buildup to Roland Garros, then going to Paris, might do more damage than good to his body.
Then all of a sudden, out go his chances at Wimbledon, which could be the grand slam where he is most likely to add to his haul of 20 majors.
For fans, just continuing to play -- and you know it would be at a high level -- would be enough.
Call it a massive surprise, for this author, if Federer -- sponsored by Japan's Uniqlo -- calls it quits prior to the Olympics in Tokyo next year, since he has never won an Olympic singles gold. And that format is the best of three sets until the final.
The fairy-tale comeback of 2017 is over but we've seen enough of Federer to never count him out.
A gentle reminder: The grand slam season is made up of four grand slams, not one.
Let's see what the rest of 2019 holds.
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