An exotic move but necessary. The rook releases the d8-square for the queen and anticipates the opening of the f-file after the e5-e6 move. Everything is still well-known. Many correspondence games prove the correctness of Black's position.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... a7a6  4. b5a4  4... g8f6  5. e1g1  5... f6e4 The Open Ruy Lopez is one of the most reliable possibilities for Black and has been used by several super GMs. 6. d2d4  6... b7b5  7. a4b3  7... d7d5  8. d4e5  8... c8e6  9. b1d2  9... f8e7  10. c2c3  10... e4c5 A variation that is in vogue and in which White has not yet been able to prove an advantage, despite the dangers for Black and the need to remember many lines. 11. b3c2  11... d5d4  12. d2b3  12... d4d3  13. c2b1  13... c5b3  14. a2b3  14... e6f5  15. f1e1  15... e8g8  16. h2h3  16... d8d7  17. b3b4  17... f8d8 An important position for the theory of this line. There are over 100 games in my database; most are played in correspondence chess. 18. c1f4  18... a6a5 A thematic move that is necessary to give life to Black's pieces. 19. g2g4  19... f5g6  20. b4a5  20... a8a5  21. b1a2 The good old Spanish bishop comes to haunt Black's king, but no one is afraid of these things when the preparation is well done.