A few thoughts:

Playing ...Nxd4 and then Bd7 will generally invite an advantageous e5, forcing ...Ne8.

As for games involving g4-g5 which went well for White, the first couple I would think of are Rachels-Browne, US ch 1989 and Tiviakov-van Wely, Groningen 1995.

I continue to be astounded, though, by questioners who repeatedly mention things like ICC blitz games, but never mention a chess book.

Gerbarts,

Kasparov explains some of this in his book, Revolution in the '70s, and has promised to explain the rest of it in the next volume of that series.  Given that the world's greatest-ever Scheveningen player is about to opine on these positions, it is probably foolhardy for me to wade in with my two cents.  But why not?  It might be fun to look back in a couple of months and find out that everything I've written below was wrong.

I think you already have the answer to your first question.  7.a4 is not considered to be necessary as 7.0-0 b5 8.Bf3 is thought to be good for White.  I agree with this and, for an example, see the famous game, Smyslov-Kottnauer 1946.  But don't discount 7..b5 8.Bf3 Ra7 completely, as some very good players have tried to make it work.

The bottom line for your purposes is that you don't have to play a4 so early -- as MNb has pointed out some players prefer to play it later so as to keep open the option of avoiding it altogether -- but if you are going to commit to an a4 system, you might as well play it on move 7.  There is no meaningful way for Black to take advantage of 7.a4 and, as John Emms notes in his Najdorf/Scheveningen book, play will usually transpose to the main lines.

As for your second question, the traditional plan with Qe1-g3 does not, imho, work so well now that White has taken the time to play a4.  For example, after 11.Qe1 Nxd4 12.Bxd4 e5, White's idea of 13.fxe5 dxe5 14.Qg3 can be met simply by 14..Bc5.  While after 13.Be3, Black gets his standard play with 13..exf4 14.B/Rxf4 Be6.  White can attempt to improve on these lines by starting with 11.Kh1 -- which may well be White's most precise move order in any event -- but even after 11.Kh1 Re8 12.Qe1 Nxd4 13.Bxd4 e5 the tactic 14.fxe5 dxe5 15.Qg3 falls short -- this time because of 15..Bd8!

Qd2 is a better and more frequently seen idea in these a4 positions.  White clears the way for the QR, gives himself the possibility of Qf2 -- a good square for the Queen -- and waits for Black to commit himself to a particular defensive set-up. 

Your third question is answered above.  After 11.Qe1, Black does not need to wait to play 11..Nxd4.  He can play it right away.  His usual plan, though, is ..e5, ..exf4, ..Be6.  Your suggestion of playing for ..Bd7 and ..Bc6 is another plan in the Scheveningen, but I don't think it works as well in this specific position.  E.g., 11.Qe1 Bd7 12.Qg3 Nxd4 13.Bxd4 Bc6 14.a5! cramping Black's queenside.  Indeed, this is a reoccuring motif in Scheveningen positions where White has in a4 and Black has played ..a6.   

As for when ..e5 works and when it doesn't, that is a question that even GMs get wrong.  I remember Karpov and Kasparov trying to  puzzle it out in their first two matches.  The key position arose after 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be2 e6 7.O-O Be7 8.f4 O-O 9.Kh1 Qc7 10.a4 Nc6 11.Be3 Re8 12.Bf3 Rb8 13.Qd2 



In their first match, Kasparov tried the immediate 13..Nxd4 14.Bxd4 e5 but it failed to equalize because of 15.Ba7 Ra8 16.Be3 Bd7 17.a5!

In the early going of the second match, Kasparov was ready with an improvement.  He played 13..Bd7 first.  Now on 14.Qf2, he played 14..Nxd4 15.Bxd4 e5 which equalizes since 16.Ba7 can now be met by Rbc8.

In the 18th game of that match, Karpov sidestepped this plan with 14.Nb3.  This pretty much forces 14..b6 (to prevent a5), when Karpov played the solid Bf2 and the game was drawn.

In the 24th game of the match, Karpov picked up the pace (after 14.Nb3 b6) with 15.g4 and, although he lost a sharp struggle, he had the better of it in the middlegame.

Later, it was discovered that g4 could be played as early as the 13th move and that this caused more trouble for Black.  Black players then began to switch from 12..Rb8 to 12..Bf8 as a way to meet this plan.  But all of that is another story, for another day.

Hope this helps,
LeeRoth
    



 

Good answer! It completely explained it to me.

I am sure I will come up with more questions for you to answer in the following days

I do not completely get it Let's say after 6.Be2 a6 (classical schveningen) 7.0-0 b5 8.Bf3 e5 what is so wrong with this line for black. I understand that white gets massive control over d5 but the bishop looks passive and besides, I never see white playing a move like Bf3 in the 6.Be2 e5 system in the Najdorf.

There has to be someone except Karpov who can explain all of this with ease considering that 6.Be2 is the most common reply to the Scheveningen.

MNb wrote on 04/30/08 at 00:34:21:


There is a "Starting Out" book that may help.  I found it useful.

All the same, if these positions are such a deep mystery to you, I would consider playing something else.

Btw.,  there is a case for reaching the Scheveningen directly via 2...e3 3. d4 cxd5 4.Nxd4 Nf6 5.Nc3 d3.

Thanks for you answer MNb. I'm not sure it enlightend me or not. Could you explain in what way white saves a tempo that you said as answer to question 3? I do not quite follow you to be honest.

Perhaps if I pose some more questions I will understand. 

Question #4
What is the general rule as to when black wants to play e5 in these sort of positions?

Hi, I have just started playing 6.Be2 against the Scveningen and Najdorf but I am not sure I understand all ideas fully and would like to ask you here at the forum. 

After 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6 6.Be2 a6 7.a4



we get to the following position and question #1:
Many times, white postpones his last move 7.a4 and plays another move instead. I suspect this has to do with some variation with the Be2 bishop going to f3 being good for white if black plays b5. Is this correct? Also, this position can be reached through the Najdorf where black has already played a6 before e6. I play the 6.Be2 variation against the najdorf aswell. Since I play both systems with white perhaps someone could explain the differences that I should keep in mind.




after the following 7...Be7 8.0-0 0-0 9.Be3 Nc6 10.f4 Qc7 we reach the following position and question #2


Here white plays 11.Qe1 and 11.Qd2

Can someone explain both of these ideas and refer me to instructive games in these variations. Is any of these moves considered theoretically superior than the other. The games that I have looked at so far do not make a lot of sense to me. White tries to attack but I have seen very few games so far that give him any good attacks. Most of the times the attacks white gets look kind of superficial and almost weakening. I'm I right, or am I only looking at the wrong games. Ofcourse I have seen games at lower levels where white simply overruns white with g4-g5 etc. but the games between better players tend to be more difficult. The games I play online have also proved this to me. I am usually afraid of pushing g2-g4 against 2000+ players on ICC because they seem to better know what they are doing than myself.

Please give me tips of some games between top gms where whites crushes black in these variations for me to learn.


Further, after 11.Qe1 Bd7 white plays 12.Nb3 which I understand prevents black from playing the maneuver NxN, Bc6. 


My final and last question however (question 3) is: Why does black have to wait with playing NxN? Couldn't he have played this move at least one move earlier and later played Bd7-c6. What is the difference?

Hopefully some nice person has time to answer my questions. I appreciate all the help I can get and will hopefully be able to give back some knowledge as I get better at chess.

Cheers