user-1: The world elite usually practises extremely deep opening preparation based on established theory, with the first move that has never been played before often coming after the 20th turn.
What are some recent (last 20 years) examples of top-class players deviating from theory early (say, on the 8th move or before)?

user3890: The most bold novelty I have seen in recent chess is definitely the one played by Richard Rapport against Leinier Dominguez Perez on the 2014 Tata Steel tournament. You can find the game here. As a peek of the game, the first moves were:
[FEN ""]
[White "Richard Rapport"]
[Black "Leinier Dominguez Perez"]

1. c4 c5 2. Nc3 g6 3. g4!!

I find that Richard Rapport is a player that will most likely shock your chess, no matter what level do you have. He plays unconventional and uncompromising chess, trying new things against the best players. Even in this tournament, one of the best of the year, he played innovative chess in many of his games.
For a compilation of all his games in said tournament, click here.

user924: Another famous example is Zvjaginsev in the Russian Championship Superfinal 2005, against ex-FIDE World Champion Khalifman:
[FEN ""]
[Event "ch-RUS Superfinal"]
[Site "Moscow RUS"]
[Date "2005.12.20"]
[EventDate "2005.12.19"]
[Round "2"]
[Result "1-0"]
[White "Vadim Zvjaginsev"]
[Black "Alexander Khalifman"]
[ECO "B20"]
[WhiteElo "2659"]
[BlackElo "2653"]
[PlyCount "73"]

1. e4 c5 2. Na3 Nc6 3. Bb5 Qc7 4. Nf3 g6 5. c3 a6 6. Bxc6 Qxc6
7. O-O Bg7 8. d4 d6 9. d5 Qc7 10. h3 Nf6 11. Bf4 O-O 12. Re1
b5 13. Qd2 Bb7 14. Rad1 Rfe8 15. c4 Qb6 16. Bh6 Bh8 17. b3 e6
18. Ng5 exd5 19. cxd5 Re7 20. Re3 Rae8 21. Rde1 a5 22. Nb1 b4
23. Qc2 Nd7 24. Nd2 Ba6 25. Ngf3 Ne5 26. Bg5 Nxf3+ 27. Nxf3
Rd7 28. e5 dxe5 29. Nxe5 Rxd5 30. Nxf7 Rxe3 31. Rxe3 Kxf7
32. Re7+ Kf8 33. Qe4 Rd1+ 34. Kh2 Qd6+ 35. f4 Bf6 36. Bh6+ Kg8
37. Qa8+ 1-0

After 2.Na3!? Khalifman allegedly pointed at the knight and laughed out loud, but he still lost in the end. Zvjaginsev repeated the move quite a few times afterwards and other GMs have played it.
In general, novelties after move 20 are quite rare. Yes some opening theory goes that deep, and sometimes those lines are played, but especially the absolute top GMs tend to avoid such lines because the earlier both players are thinking on their own, the higher the chance the better player wins. Between move 10 and 15 is probably about normal.

user3270: Aronian vs Anand at Candidates 2014 (http://www.chessgames.com/perl/chessgame?gid=1751406) was out of theory after Black's 3rd move, but only because White played an extremely odd opening which will probably never be repeated at the top level.
Aronian vs Leko at Morelia-Linares 2008 (http://www.chessgames.com/perl/chessgame?gid=1486033) featured a strong novelty on White's 9th move.

-1: <p>The world elite usually practises extremely deep opening preparation based on established theory, with the first move that has never been played before often coming after the 20th turn.</p>

<p>What are some recent (last 20 years) examples of top-class players deviating from theory early (say, on the 8th move or before)?</p>
 3890: <p>The most bold novelty I have seen in recent chess is definitely the one played by Richard Rapport against Leinier Dominguez Perez on the 2014 Tata Steel tournament. You can find the game <a href="http://www.chessgames.com/perl/chessgame?gid=1744313" rel="nofollow">here</a>. As a peek of the game, the first moves were:</p>

<pre><code>[FEN ""]
[White "Richard Rapport"]
[Black "Leinier Dominguez Perez"]

1. c4 c5 2. Nc3 g6 3. g4!!
</code></pre>

<p>I find that Richard Rapport is a player that will most likely shock your chess, no matter what level do you have. He plays unconventional and uncompromising chess, trying new things against the best players. Even in this tournament, one of the best of the year, he played innovative chess in many of his games.</p>

<p>For a compilation of all his games in said tournament, click <a href="http://www.chessgames.com/perl/chess.pl?tid=82986&amp;pid=123427" rel="nofollow">here</a>.</p>
 924: <p>Another famous example is Zvjaginsev in the Russian Championship Superfinal 2005, against ex-FIDE World Champion Khalifman:</p>

<pre><code>[FEN ""]
[Event "ch-RUS Superfinal"]
[Site "Moscow RUS"]
[Date "2005.12.20"]
[EventDate "2005.12.19"]
[Round "2"]
[Result "1-0"]
[White "Vadim Zvjaginsev"]
[Black "Alexander Khalifman"]
[ECO "B20"]
[WhiteElo "2659"]
[BlackElo "2653"]
[PlyCount "73"]

1. e4 c5 2. Na3 Nc6 3. Bb5 Qc7 4. Nf3 g6 5. c3 a6 6. Bxc6 Qxc6
7. O-O Bg7 8. d4 d6 9. d5 Qc7 10. h3 Nf6 11. Bf4 O-O 12. Re1
b5 13. Qd2 Bb7 14. Rad1 Rfe8 15. c4 Qb6 16. Bh6 Bh8 17. b3 e6
18. Ng5 exd5 19. cxd5 Re7 20. Re3 Rae8 21. Rde1 a5 22. Nb1 b4
23. Qc2 Nd7 24. Nd2 Ba6 25. Ngf3 Ne5 26. Bg5 Nxf3+ 27. Nxf3
Rd7 28. e5 dxe5 29. Nxe5 Rxd5 30. Nxf7 Rxe3 31. Rxe3 Kxf7
32. Re7+ Kf8 33. Qe4 Rd1+ 34. Kh2 Qd6+ 35. f4 Bf6 36. Bh6+ Kg8
37. Qa8+ 1-0
</code></pre>

<p>After 2.Na3!? Khalifman allegedly pointed at the knight and laughed out loud, but he still lost in the end. Zvjaginsev repeated the move quite a few times afterwards and other GMs have played it.</p>

<p>In general, novelties after move 20 are quite rare. Yes some opening theory goes that deep, and sometimes those lines are played, but especially the absolute top GMs tend to avoid such lines because the earlier both players are thinking on their own, the higher the chance the better player wins. Between move 10 and 15 is probably about normal.</p>
 3270: <p>Aronian vs Anand at Candidates 2014 (<a href="http://www.chessgames.com/perl/chessgame?gid=1751406" rel="nofollow">http://www.chessgames.com/perl/chessgame?gid=1751406</a>) was out of theory after Black's 3rd move, but only because White played an extremely odd opening which will probably never be repeated at the top level.</p>

<p>Aronian vs Leko at Morelia-Linares 2008 (<a href="http://www.chessgames.com/perl/chessgame?gid=1486033" rel="nofollow">http://www.chessgames.com/perl/chessgame?gid=1486033</a>) featured a strong novelty on White's 9th move.</p>
