# Why did Carlsen play 7. dxc5 in Game 7 of the 2018 World Championship?

As a class A player, I have some understanding of opening principles. Relevant to the move played in the game, I know that it's advantageous to control the center, to have central pawns controlling the center, and to maintain tension for as long as possible. It's for these reasons that I was confused by 7. dxc5 in game 7 of the world championship.

I would understand this move if Carlsen followed it with 8. cxd5, giving black an isolated queen pawn and trying to play against this for an advantage. But Carlsen did not follow up with this idea, and I was unable to understand the strategy of his next moves.

What's the idea behind 7. dxc5 in this game? Why give up a central pawn and break tension? Here's a link to the game where it can be replayed: Chessbase.

• Opening principles are only a first approximation anyway. The higher the level, the more concrete chess becomes. (Not an answer to your question, but worth noting.) Commented Nov 19, 2018 at 11:58
• Also worth noting that if you dont take you might yourself end up in an isolated pawn position since in cxd4 it gets a little odd recapturing with either the knight or queen
– Isac
Commented Nov 19, 2018 at 12:05
• @DagOskarMadsen Yes, that's a good point and one that I've heard while listening to commentary of this match. Concrete calculations often trump principles or first impressions. Commented Nov 19, 2018 at 12:08
• @Isac Yes, another good point and I also thought of that. Perhaps by taking white avoids getting an IQP himself and reserves the option of giving black an IQP in the future (without doing so immediately). Commented Nov 19, 2018 at 12:09
• @user929304 Yes, it's a great answer, although I haven't yet read all of the annotations that he gave. I might wait until I have a chance to go through them. Commented Nov 21, 2018 at 10:52

The same move order also occurred in game 2 (at least up to `9...Qa5`). It's a good question that you're asking, though I'm afraid there's no intuitive answer in the way that you're looking for. Instead, these are very concrete lines well polished by computer analysis, which means the best way to understand a decision such as `7.dxc5` is to simply play through the lines a bit, and consider a couple of alternatives in order to draw close analogy between these QGD lines and pinpoint the main differences with and without `dxc5.`

That said, part of the answer also simply lies in the strategies that the players have adopted in this match (which ultimately stems from their exact preparations), e.g., Caruana seems to favour these rather more solid lines with `4...Be7` as opposed to the somewhat sharper variations such as the Vienna (`4...dxc4`), Tarrasch (`4...c5`) or Ragozin (`4...Bb4`) to name a few, most of which by the way Caruana has himself played previously. But then `4...Be7` essentially allows Carlsen to stay in the mainline theory of QGD with `Bf4` and `e3...`, and from Caruana's point of view, it's the `6...c5` variation that he seems to have chosen to prepare for and play in this match against this line (so you should remember the line as `Be7`... `c5`, as the key defining moves of this variation), which he has followed similarly in both games with this `Nc6` and `Qa5-Rd8` or `Qa5-Qd8` ideas.

Now here's my attempt to offer you a bit of intuition for the specific `7.dxc5` variation, but do take it with a grain of salt as these (like most other Queens pawn openings) are inherently very concrete lines after all: (annotations added to all variations and sub-variations)

`````` [title "London WCC2018 7.dxc5 in QGD games 2&7"]
[fen "rnbq1rk1/pp2bppp/4pn2/2pp4/2PP1B2/2N1PN2/PP3PPP/R2QKB1R w KQ - 0 7"]

Hopefully, the above analysis (by no means exhaustive) offers you a glimpse of the kinds of ideas that underlie the `dxc5` line. But bear in mind that, in general, to answer such questions for yourself, try to uncover not only the concrete aspects of what the move achieves, but also the sorts of ideas it prevents or side-steps.