CAMELOT FANTASIES

For some of the reason's you say. 

1. He had not been that strong against the very top players because of getting beaten early in his career and often, and of course their "aura".  This produces a lack of confidence.  He was in a sense beaten before walking on the court.   However, once he got very close to Djokovic last year, his confidence improved, especially against him.  He needs a similar match or matches against Nadal and Federer to lift his confidence for them.  He might be ready to do that with Nadal now off his recent huge victory vs. Nole.  But confidence, though very important, is not the only factor.

2., Stan's movement side to side was not so great in years past which is very essential against the best.  He was basically just too slow and lacked stamina.  With most of the tour's courts playing medium or slower, it was difficult for him to stay with the best movers with stamina. His footwork is generally pretty good, but he occasionally goes off balance.  Even though his side to side movement has improved a lot with his more recent fitness improvements, it still is below the likes of Nadal, Djokovic, Murray, and Federer on one of his good days.  But there are not many that move as well all match long as those players other than maybe Ferrer. 

3. Stan has the same problem as other one handed backhands against left-handed Nadal.  It's very difficult to put much on the ball when it is bouncing shoulder height or higher.  I think you would have to be quite tall to be able to deal with it with a single hander.

I think those are the 3 main reasons.  There may be others like Rafa forcing Stan into making errors with his good defense..

If you look at the most recent head to head between them, Stan has been making inroads, playing a very tight match in their last meeting at the World Tour Finals losing in two tight tiebreakers.  He has been failing better, as his Beckett tattoo says.  Now, I think he has all the tools, is moving better, and so forth.  He just needs the belief vs. Nadal.  His win over Djokovic should help, but Rafa is still a beast when he is playing well.  Belief against one player doesn't necessarily translate to belief against every player.  It's easy to get down on yourself when believe you are playing well but still being beaten because the guy on the other side refuses to give in, gets fortunate, or is just better on the day.   Sometimes, once you break through against someone, you can turn the rivalry around.  Sometimes no.

Let's see what happens tomorrow. 
Stan had two days off vs. Rafa's one.  That should give him a bit of an advantage, but we know how good Rafa is at recovering.
I'd like to see a good, competitive match (not 3 sets), so I'm going to predict (and hope) that Stan takes the first set in his career from Rafa this match.  If it comes early, all the better.  He might gain tremendous confidence.  But Rafa has to be overflowing with motivation.  He is so close to tying Sampras and winning his second career slam, he must be salivating.  It might create more pressure, or not.  We will have to see what happens. 

I think the key to the match for Stan will be how well Stan can hit his backhand down the line to Rafa's backhand and keep Nadal pinned there, until the ad court is wide open for an inside-out angled winner.  Roger couldn't execute it this time.  Stan can't stay back too far, because I think Rafa will drop shot him.  Stan has been mixing pace well, sometimes pushing slower deep balls, and then really exploding shots when he gets in a good position on the court.  It's a bit risky against someone like Nadal to push too often and too slow.  If the ball comes up a little short, Rafa will punish it.  Stan's serve really helped him out of tight spots (love-30) against Djokovic and Berdych.   He'll need to serve well today to keep Rafa on his heels and guessing.

For Rafa, he needs to continue to keep his shots deep and his backhand cross court working and keep Stan off balance when he comes to net.  He needs to return well against Stan's big serve and hope Stan isn't putting a lot of first serves in.  It's critical he does something with Stan's second serve.  He just can't push it across to the service line.  Rafa needs to serve at least as well as yesterday, maybe a bit better.
And of course, he needs to keep his errors down and force Wawrinka to go for too much and make the errors.

Much as I would love Spartan Stan to get his first Grand Slam win ever, I still have to go with Nadal, probably in 4, but I wouldn't be shocked with any result.

That's how I see it Lady TT.

Respectfully,
masterclass