This is the new trend, according to Megabase, that outshines the older 9.Nbd2.
1. g1f3  1... d7d5  2. g2g3  2... g7g6  3. f1g2  3... f8g7  4. d2d4  4... g8f6  5. e1g1  5... e8g8  6. c2c4  6... c7c6  7. b2b3 Carlsen used a version of this solid line to defeat Nepomniachtchi in their final test before their world championship match. 7... c8f5 The main line. 8. c1b2  8... b8d7 