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.
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.