This idea was played several times during the match. It's a relatively uncommon move within the gigantic world that is the Sicilian Najdorf.
1. e2e4  1... c7c5  2. g1f3  2... d7d6  3. d2d4  3... c5d4  4. f3d4  4... g8f6  5. b1c3  5... a7a6  6. f1e2  6... e7e5  7. d4b3  7... f8e7 