Who's the greatest?
It seems absurd that events in a different sport can influence another, but doesn't Roger Federer's Wimbledon success further shorten the odds on a Tiger Woods win at the Open?
Federer's record-breaking 15th Grand Slam title generated a congratulatory text from the Woods mobile just as soon as Tiger had wrapped up business in Bethesda where he enjoyed his latest PGA Tour win at the Congressional Country Club.
"We texted," said Woods. "He won the French and I won Memorial, so it was kind of let's do it on the same day, let's do it again today. That would be nice. His are a hell of a lot bigger than mine, though. He won two Slams and I won two Tour events. Hopefully I can get the majors now."
The two greatest individual sports stars of our time (who don't propel darts for a living) are big buddies. They have us believe their bond is down the unique insight they share on how to utterly dominate a global sport.
Their conversation topics must include how to keep the opposition down, the media at arms length and how to make sure the noughts keep being added to the sponsor contracts they share.
They act as spokesmen for each other, bigging up the other's triumphs and excusing their disappointments. "And most people forget he was ill then," Woods has said many times to explain Federer's failure to win the 2008 Australian Open.
These two do share much in common and being mates makes a lot of sense at all levels. Tiger will be dispensing nappy changing and night feed advice before long.
But, perhaps more significantly, they remain big rivals as well. The BBC Television commentary on Federer's epic win over Andy Roddick duly noted that the great Swiss had rolled past not just Peter Sampras in the major stakes "but also Tiger Woods."
What was a golfer doing muscling in on such a huge moment for tennis?
Well, it is a reflection of how intertwined the careers of these two have become and it provides a reason why Woods becomes an even more dangerous prospect at Turnberry.
And this makes me wonder whether Federer is in some way Woods' biggest rival? Certainly no current golfer comes close to Tiger's achievements and it is hard to imagine one emerging soon.
So do we have to look to another sport to identify a true rivalry? If we do, then we should look no further than the six-time Wimbledon champion.
It was a question that floated around throughout my time at Wimbledon (I hot-footed there for 5 Live straight from the US Open). Inevitably the other was who the greater sportsman, Federer or Woods?
The nature of the Federer's extraordinary victory will surely have nudged him to the front, just as Woods' US Open win on one leg last year (combined with Rafael Nadal's rise in tennis) had the American golfer ahead.
It's a fascinating argument with no definitive answer - and the fact that golfers don't have to run to play their sport is irrelevant. It is a debate about the skill and nerve required to beat all comers at games played the world over.
It is a story of two great competitors from two great sports plying their trade simultaneously at a level rarely seen before.
Yes, there is an element of comparing apples with oranges here but there is enough common ground to still make the discussion as tasty as the best fruit salad.
Top golfers and tennis players share much mutual respect. That was evident from the golfing talent that joined us in the 5 Live Wimbledon commentary box over the fortnight - Sergio Garcia, Rory McIlroy and Graeme McDowell all joined us and Adam Scott was also spotted at the All England Club.
But back to the two arguably biggest individual sportsman in the world. Federer moved from 13 to 15 Grand Slams to eclipse Sampras' major record by winning the French Open and then Wimbledon in quick succession.
Were Woods to perform at a similar level and capture the Open and PGA, Federer would be playing catch up again by the time he arrives at Flushing Meadows for his US Open defence at the end of August. This fact will surely not be lost on Woods.
Indeed, both would like nothing more than to continue a tit for tat rivalry and for the golfing world that means Woods will be as motivated as ever at Turnberry and Hazeltine.
Mind you, that would have been the case anyway - competitors at this level don't tend to need any extra gee up. Not that that should stop the discussions thrown up by the greateness of these two extraordinary athletes.