Great Players - Who played who?

Yeah... there are about 10,000,000,000 threads around here about "who is the greatest evaaaahhhhhr player for all eternity."  Yawn.

My question is about who had the chance to play who historically, PROVING who was the better player!

Example:  Most of us know that Staunton avoided playing Morphy while he was in Europe, raising the question for all time which of the two was the stronger player.  Most people will probably side with Morphy on this one, but because the games never happened (at least any that we know about!), it will forever be speculation.

Blackburne obviously never played Fischer, different time periods and different outlooks on chess in any case.  However...

Did, for example, Botvinnik ever play Nimsowitsch?  Tal and Kasparov ever take a crack at a few friendly games?

Love to hear about examples from this not often discussed topic of chess history!

More people than there are who care about your useless moronic posts... that's for sure!

Just saying.

By that logic "I am the greatest player because I haven't played them yet and if I did, I would win but I didn't but I didn't lose to them."