1. e2e4  1... e7e5  2. g1f3  2... g8f6  3. f3e5  3... d7d6  4. e5f3  4... f6e4  5. d2d4  5... d6d5  6. f1d3  6... f8e7 6...Bd6 is the favorite move of Nepomniachtchi, the biggest specialist in the Petroff Defense today. For this reason, the move has become very popular. But there's nothing wrong with the development of the bishop on e7. 7. e1g1  7... c8f5  8. f1e1  8... e8g8  9. c2c4  9... b8c6 [%c_effect c6;square;c6;type;GreatFind;persistent;true] This is more accurate than 9...c6. 10. c4d5 