I'm surprised to hear what Roger Federer had to say after Switzerland's Davis Cup win over the Netherlands because, up until then, all his public utterances had been really positive. Federer was enjoying his tennis, enjoying his life and family. It all came together perfectly at Wimbledon, although the Olympics and US Open would have been blows. Perhaps his failure in New York is what is making him feel "wounded" and "exhausted", and that the hurt is mental.
The Olympics was very strange — I couldn't understand his performance in the final, unless he was over-burdened with stress because he wanted it too much, which was a concern I raised before the Games. Some people read it as if he looked like he wasn't bothered, which was nonsense. There is another possible reason for his somewhat muted display, and that was the epic semi-final against Juan Martin Del Potro. While Federer's playing style does not wear him out as much as the other guys, it was a mammoth match and perhaps that left him in a weaker position for the final.
I think there was an element of fatigue, but the likelihood for me is he was shackled by his weight of expectation and desire as it was the only thing he hadn't won, the biggest thing he hadn't won.
So perhaps when that happened he suffered a bit of a comedown, a comedown which followed him into the US Open. Going out in the quarters would have left him thinking "well what's next, where's my motivation"? Doing well in the Davis Cup is a boost but is it enough to reinvigorate a man who was won everything, who has more money than he'll ever need, and who has been supremely motivated for a very long time?
It's natural to lose your motivation as an athlete after many years at the top; it would be inhuman not to ease off, eventually. Normally in sports it's the body that speaks first, but in Federer's case his style does not expend as much energy as the other top players — certainly not compared to Rafael Nadal, Novak Djokovic and Andy Murray — so his desire may well be waning first.
If he has lost his motivation it had better be temporary and he had better get it back quick, as Murray is only going to get better, while Djokovic is not going to fade any time soon.
On any surface but grass, even some of the lesser players will see Federer as beatable and will be snapping at his heels, so for me it's the Australian Open that will tell us where Roger is — while it's a good tournament, the World Tour Finals in London is not the major event they would like you to believe.
The Australian Open will signal either the beginning of the end for Roger, or the start of an Indian Summer. He doesn't have to win in Melbourne, and I still think Wimbledon is his best chance of success in the Slams next season. But if he is beaten in the third or fourth round by a Philipp Kohlschreiber, then that could well be it for Roger, although he will continue to be a threat at Wimbledon even in an average season.
Physically Roger can play for another three or four years, but it's a question of motivation now and — even if it's just a tiny drop — the effects are huge at this level.
Another man who we should be worried about is Nadal. No one really knows what's going on with Rafa at the moment, although there are whispers in Spain that he will play in the Davis Cup.
To play at his level of intensity, with his power, in so many tournaments, to such a high level, for almost a decade ... that kind of punishment leads to a shorter career and you have to worry whether he will come back from this continued setback.
We've seen him return before though, coming back stronger than ever after tendonitis ruined his 2009 season, responding to the doubters by winning three of four Majors and completing the career Grand Slam by finally taking the US Open title.
But repeated knee problems are hugely concerning and you wonder whether he will be able to sustain runs to finals, particularly seeing as his favoured surface of clay is the one that makes for the longest, most gruelling matches.
If Rafa comes back strongly either at the Davis Cup or in Melbourne, it would be a remarkable story and one that would make for a continuation of this golden generation of the men's top players. But it's a big ask.
I can see Murray and Djokovic dominating the men's game for a few years now. The best of the rest for me has to be Juan Martin Del Potro but, despite his early-career US Open win, I just don't think he's got the game to be a number one, not with those two about, or even with a fading Nadal and Federer in the top four.
When the likes of Sam Querrey are being touted as possible stars, you know the challengers are fairly weak. The likes of Grigor Dimitrov and Bernard Tomic have bags of natural talent, but they seem to lack the mentality to realise this potential.
Dmitrov needs structure and management, but he dispensed with the coach that gave him this — Peter McNamara — because he didn't like having to work so hard. Tomic, on the other hand, has been handled with kid gloves by the Australian federation, who in my view have been soft with him. This could work for the boy long term, but right now he seems to be stalling. If he matures and focuses, he is a very bright prospect, but it's a big if.
David Goffin is an example someone who has the technical ability and mentality for success, but is just too small for the modern game, which requires a minimum level of power that a man of his height and build can't generate. That seems to be culling a lot of the gifted young players from the men's game, as success comes later and to the bigger athletes.
Murray has the Grand Slam monkey off his back and, already a physical specimen for the past few years, is crucially also improving technically and mentally as he gets older.
As a result, it's between him and Djokovic, who will win Slams but is not as invincible as he was at his 2011 peak. I can see them sharing the majority of the big tournaments between them for a few years now, unless Roger and Rafa come back from the brink.