MNb wrote on 03/05/11 at 03:31:41:

... and so does Uhlmann. I think some sources even label 6.a3 a mistake due to 6...Qa5.

Strong Whites have usually played (after 5.Qg4 Ne7) 6.Bd2 or 6.dxc5 instead. But I notice that some reasonbly strong players have tried 6.a3 in recent years; maybe it's not as bad as usually thought? If so it could be a way to avoid the 6...Qa5 main line, though 6.a3 Qa5 should still not be worse for black.

For reference:

[Event "DDR-ch 30th"]
[Site "Fuerstenwalde"]
[Date "1981.??.??"]
[Round "12"]
[White "Paehtz, Thomas Sr"]
[Black "Uhlmann, Wolfgang"]
[Result "0-1"]
[ECO "C17"]
[WhiteElo "2380"]
[BlackElo "2475"]
[Source "ChessBase"]

1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 c5 5. Qg4 Ne7 6. a3 Qa5 7. Bd2 cxd4 8. axb4 Qxa1+ 9. Nd1 Nbc6 10. Nf3 Bd7 11. Qxg7 O-O-O 12. b5 Nf5 13. Qf6 Na5 14. g4 Nc4 15. gxf5 Nxb2 16. Be2 Bxb5 17. Nxd4 Bxe2 18. Kxe2 Nxd1 19. Be3 Nc3+ 20. Kd3 Qxh1 21. Kxc3 Qe1+ 22. Kb2 Qb4+ 23. Nb3 Kb8 24. Bc5 Qb5 25. Qxf7 exf5 26. e6 a5 27. e7 Rc8 28. Bd4 Rhe8 29. Ka3 0-1

[Event "TCh-NED 2008-9"]
[Site "Netherlands NED"]
[Date "2009.03.28"]
[Round "7"]
[White "Cuijpers, F."]
[Black "Jussupow, Ar"]
[Result "1/2-1/2"]
[ECO "C17"]
[WhiteElo "2497"]
[BlackElo "2587"]
[Source "Mark Crowther"]

1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 Ne7 5. Qg4 c5 6. a3 Qa5 7. axb4 Qxa1 8. Kd1 cxd4 9. Nb5 O-O 10. Nc7 Bd7 11. Nxa8 Nbc6 12. b5 Nb4 13. Qxd4 Nxc2 14. Qc5 Rxa8 15. Qxe7 Qa4 16. Qxd7 Nb4+ 17. Ke2 Qc2+ 18. Kf3 Qxc1 19. Ne2 Qxb2 20. Qxb7 Rf8 21. Qxa7 Qxe5 22. Qd4 Qd6 23. g3 e5 24. Qd2 d4 25. Kg2 Rc8 26. Nc1 Rc2 27. Qe1 d3 28. Nxd3 Qd5+ 29. Kh3 Qd7+ 30. Kg2 Qd5+ 31. Kh3 Qd7+ 32. Kg2 Qd5+ 33. Kh3 1/2-1/2

[Event "16th FAJR Open"]
[Site "Urmia IRI"]
[Date "2008.02.06"]
[Round "6"]
[White "Moosavian, S."]
[Black "Grigoryan, Av"]
[Result "1/2-1/2"]
[ECO "C17"]
[WhiteElo "2349"]
[BlackElo "2509"]
[Source "Mark Crowther"]

1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 Ne7 5. Qg4 c5 6. a3 Qa5 7. Bd2 cxd4 8. Bb5+ Bd7 9. Qxd4 Nbc6 10. Bxc6 Nxc6 11. Qg4 d4 12. Qxg7 O-O-O 13. Ne4 Rhg8 14. Qf6 Bxd2+ 15. Nxd2 Nxe5 16. O-O-O Qc7 17. Kb1 Rxg2 18. Nh3 Ba4 19. Rc1 Bc6 20. Rhe1 Ng4 21. Qh4 Qxh2 22. Nf1 Qc7 23. Re2 Bf3 24. Rd2 f6 25. Ng3 Rh2 26. Rd3 Ne5 27. Qxf6 Nxd3 28. cxd3 Bc6 29. Ng5 Re8 30. N3e4 Rh5 31. Nxe6 Rxe6 32. Qxe6+ Kb8 33. Nd6 Qd7 34. Qg8+ Kc7 35. Ne8+ Kb6 36. Nf6 Qf5 37. Nxh5 Qxh5 38. Qd8+ Ka6 39. Qxd4 Qf3 40. Qc4+ Bb5 41. Qe6+ Ka5 42. Rc3 Qd1+ 43. Ka2 Bc6 44. Qb3 Qh1 45. d4 b6 46. Qb4+ Ka6 47. Qc4+ Bb5 48. Qc8+ Ka5 49. b4+ Ka4 50. Rc1 Qd5+ 51. Ka1 Qxd4+ 52. Qc3 Qxf2 53. Rb1 Qf7 54. Kb2 Qf2+ 55. Ka1 Qf7 56. Qc2+ Kxa3 57. Qc1+ Ka4 58. Qd1+ Ka3 59. Qc1+ Ka4 60. Qc2+ 1/2-1/2

After 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 c5 5.Qg4!? Ne7, what happens if white now plays 6.a3(?)

Granted, 6...Bxc3+ bxc3 is a main line Winawer, but this is a problem for those who intend to play the Qa5/Qa4 variation.

Is 6...Qa5, 6...cxd4, or 6...Ba5 the answer?