comment: An almost new move in this position (it was played in just one game), but a well-known plan from modern games. Historically, Black didn't play this way, advancing the queenside, but computers have shown that this is a viable plan. This active plan has transformed the orthodox from a reliable but somewhat passive defense into as good a weapon for playing for a win as any other.
context: 1. d2d4  1... d7d5  2. c2c4  2... e7e6  3. b1c3  3... g8f6  4. c4d5  4... e6d5  5. c1g5  5... f8e7  6. e2e3  6... c7c6  7. f1d3  7... b8d7  8. g1e2 The knight development on e2 was Kasparov's favorite. White can wait by playing 8.Qc2 before deciding where the knight goes, or he can also play 8.Nf3. 8... d7f8 Many ideas have been developed recently to give a new flavor to Black in the Exchange Variation of the Queen's Gambit. This move is one of those ideas. It's the first time Caruana has played it. 9. d1c2  9... f8e6  10. g5h4  10... g7g6  11. a1d1 Played in just two games, but we will have a transposition in the next move. 11... e8g8  12. e1g1 With the rook on d1, it's clear that White is intending the typical plan with f3-e4.