I dunno if this is right, but from a very quick look:
Nxd4 Nxd4 exd4 Qxd4 c5! Queen moves and c4 winning the bishop.
White does play d4 in the Ruy, but c3 first (which also gives the bishop an escape square if Na5).
d4 in the Ruy Lopez
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White has better position with the c3 advance prior to d4. Note that Be3 cannot be played in either variation due to Nxe4, winning a pawn and getting control of the e file. Most theoreticians and higher level players like the c3 preparation as it also has one good point not mentioned either: the c6 Knight cannot obtain the outpost at d4 later where he can radiate control in conjunction with the other pieces of e2 and f3 as well as c2 and b3.
Na5?! for Black becomes a problem as now you have a rim Knight only controlling 2 squares, b3 and c4. This places him 2-3 moves from helping in the King side attack and relegates him to helping establish a Queen side pawn majority attack later.
d4 can be played independently of c3 if and only if White enters the Exchange Variation as the f8 bishop is suited at c5 or even e7. Bd6 interferes with the Queens line of attack and is not a favorable line. Play tends to be sharp in the d4 line of the Exchange so unless you are good at tactical and positonal play, this might be a line to steer clear from.
Still, remember that although many lines to the Ruy Lopez have been analyzed out as far as move 30 and beyond, a great deal of area is still unclear.
IMHO, if you want to see some of the more creative ideas in the Ruy, look into some of the World Champion Correspondence Games as some of these can refute a lot of lines in their sheer creativity.
Pfren is right it is playable, though the burden of knowing how to follow in the play rests on White. I see the line being somewhat sharp for both players but then again, I play c3 then d4 almost as habit.
Thanks, that's all good advice. Appreciate the clarifications.
one of our most experienced players at my club recommends d4 without c3 initially in the Royal opening and it certainly has its merits at the time he suggested it to me during a game analysis i didnt think much of it but that was based on my book knowledge now in light of his practical experience it is yet another chapter to add to my never ending chess book
I've been trying to find an answwer as to why it is not a good idea for white to play d4 in the Ruy. I've tried to find games where d4 is played early, but cannot seem to find it. I assume then, it is poor play, but I don't know why.
I've given three possible places where I've seen it (and have the urge to play it myself) in the diagram below.
Now, maybe, as I assume, this is an issue about the e4 pawn. Sometimes, the e4 pawn can be defended - either by O-O with Re1 or Nc3. In such cases, does it then make sense to play d4?