In the online chessbase I can only find one game with 10. Na3 after the sequence 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 d6 5.c3 f5 6.exf5 Bxf5 7.O-O Bd3 8.Re1 Be7 9.Re3 e4, a game where Timman beat IM Poetsch after 10. Na3 Nf6  11. Ng5?



Timman responded 11...Qd7 and won, though another possibly simpler option is 11...d5

It appears that 10. Na3 was not an innovation though, there are a couple of games from the ICCF archives from 2013 that featured the sequence 10...Nf6 11. Ne1 O-O 12. Nxd3 exd3 13. Rxd3 d5 instead, one a draw, the other a win for White.



14.Bxc6 may not be optimal; the following win for White features 14.Bc2 instead



I had 10. Na3 played against me twice on FICGS in the past month or so, and at first I was concerned that White was a clean pawn up after the sequence 10.Na3 Nf6 11.Ne1 O-O 12.Nxd3 exd3 13.Rxd3.  In any case I played 13...d5 in both games as in the games from ICCF above, and in one game that is still ongoing my opponent played 14.Re3 when after 14...d4 15.Rh3 b5 Black seems equal.  However my opponent went astray with 15. Re1? when 15...b5 is still indicated but has led to a sizable advantage for Black:



And Black has the pleasant choice between 21...Qg5 and 21...Qh4

My other game just ended as drawn.  My opponent proceeded with 14. Bc2 as in one of the games above but I think I improved over 14...Bxa3 with 14...Bc5, though I was also considering 14...Qd7



And Black gets his pawn back after 25...Rxf8  26. g3 Nxf2.  Is this the last word or can White improve?