user4223: In online games I sometimes have this happen:
[fen ""]

1.d4 d5 2.c4 c6 3.Nf3 e6 4.Nc3 dxc4

and Black plays the famous "Noteboom variation".  I checked my database and I have in fact lost every single game as White where this variation happened. Usually Black just arranges his pieces nicely and pushes the a-pawn and b-pawn and I lose material due to pieces getting trapped in the corner, or having to give up pieces to stop the pawns promoting.
What is a promising way to meet this system for White?
Note: Of course, I could avoid the line with 4.e3 going into a normal Meran. But I often play quickly the first few moves of an internet game and carelessly make a natural developing move with the knight. It would be good to know how to recover from this.

user8209: In this variation, black is behind development after
[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[WhiteELO "?"]
[BlackELO "?"]
[SetUp "1"]
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/2pP4/2N2N2/PP2PPPP/R1BQKB1R w KQkq - 0 1"]


1. Bf4 Bb4 2. e3 Bxc3+ 3. bxc3 b5 4. a4 Nf6 5. axb5 cxb5 6. Rb1

White has more center control, and black will probably have a backward pawn if he tries to hang onto c4.
Another variation I like is
[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[WhiteELO "?"]
[BlackELO "?"]
[SetUp "1"]
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/2pP4/2N2N2/PP2PPPP/R1BQKB1R w KQkq - 0 1"]

1. e3 b5 2. b3 Bb4 3. Bb2 cxb3 4. Qxb3 Bxc3 5. Qxc3 Nf6 6. Bd3

which creates lots of attacking chances for white. 

user4588: In order to avoid the sharp positions where black has the connected passed a- and b-pawns, white can switch to systems with g3. This is what white opted for in Nakamura-Ivanchuk and Giri-Caruana.
In the first game, Nakamura played 5.g3. If black replies with 5....Nf6, then the game transposes to a theoretical line that arises after 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6 5.g3 dxc4.
Instead, Ivanchuk tried to postpone Nf6 and played 5....b5 6.Bg2 Bb7 7.Ne5 Qc8. However, it seems that Nakamura was able to develop a dangerous initiative.
In the second game, Giri first played 5.a4 and after 5....Bb4, he went for 6.g3, probably hoping for a good version of the 5.g3 variation.


      [FEN ""]
      [StartPly "8"]

      1.d4 d5 2.c4 c6 3.Nf3 e6 (3...Nf6 4.Nc3 e6 5.g3 dxc4) 4.Nc3 dxc4 5.a4 (5.g3 Nf6) Bb4 6.g3



4223: <p>In online games I sometimes have this happen:</p>

<pre><code>[fen ""]

1.d4 d5 2.c4 c6 3.Nf3 e6 4.Nc3 dxc4
</code></pre>

<p>and Black plays the famous "Noteboom variation".  I checked my database and I have in fact lost every single game as White where this variation happened. Usually Black just arranges his pieces nicely and pushes the a-pawn and b-pawn and I lose material due to pieces getting trapped in the corner, or having to give up pieces to stop the pawns promoting.</p>

<p>What is a promising way to meet this system for White?</p>

<p>Note: Of course, I could avoid the line with 4.e3 going into a normal Meran. But I often play quickly the first few moves of an internet game and carelessly make a natural developing move with the knight. It would be good to know how to recover from this.</p>
 8209: <p>In this variation, black is behind development after</p>

<pre><code>[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[WhiteELO "?"]
[BlackELO "?"]
[SetUp "1"]
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/2pP4/2N2N2/PP2PPPP/R1BQKB1R w KQkq - 0 1"]


1. Bf4 Bb4 2. e3 Bxc3+ 3. bxc3 b5 4. a4 Nf6 5. axb5 cxb5 6. Rb1
</code></pre>

<p>White has more center control, and black will probably have a backward pawn if he tries to hang onto c4.</p>

<p>Another variation I like is</p>

<pre><code>[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[WhiteELO "?"]
[BlackELO "?"]
[SetUp "1"]
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/2pP4/2N2N2/PP2PPPP/R1BQKB1R w KQkq - 0 1"]

1. e3 b5 2. b3 Bb4 3. Bb2 cxb3 4. Qxb3 Bxc3 5. Qxc3 Nf6 6. Bd3
</code></pre>

<p>which creates lots of attacking chances for white. </p>
 4588: <p>In order to avoid the sharp positions where black has the connected passed a- and b-pawns, white can switch to systems with g3. This is what white opted for in <a href="http://www.chessgames.com/perl/chessgame?gid=1653869" rel="nofollow">Nakamura-Ivanchuk</a> and <a href="http://www.chessgames.com/perl/chessgame?gid=1705524" rel="nofollow">Giri-Caruana</a>.</p>

<p>In the first game, Nakamura played 5.g3. If black replies with 5....Nf6, then the game transposes to a theoretical line that arises after 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6 5.g3 dxc4.
Instead, Ivanchuk tried to postpone Nf6 and played 5....b5 6.Bg2 Bb7 7.Ne5 Qc8. However, it seems that Nakamura was able to develop a dangerous initiative.</p>

<p>In the second game, Giri first played 5.a4 and after 5....Bb4, he went for 6.g3, probably hoping for a good version of the 5.g3 variation.</p>

<pre>
<code>
      [FEN ""]
      [StartPly "8"]

      1.d4 d5 2.c4 c6 3.Nf3 e6 (3...Nf6 4.Nc3 e6 5.g3 dxc4) 4.Nc3 dxc4 5.a4 (5.g3 Nf6) Bb4 6.g3
</code>
</pre>
