This is why the early bishop sortie is risky: it may  end up being locked out of the game for a long time.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1c4  3... g8f6  4. d2d3  4... f8c5  5. c2c3  5... e8g8  6. e1g1  6... d7d6  7. f1e1  7... a7a5  8. c1g5 In a must-win situation, Carlsen chooses a risky line. 8... h7h6  9. g5h4 