A somewhat offbeat move order, but it has been played by Ding and other elite players. 6.Nf3 is more popular.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. e2e3  4... e8g8  5. c1d2 Once again a new opening is played in the match. 5... d7d5 