comment: Preventing any Ng4 tactics when the bishop goes to e3.
context: 1. f2f3 A strange first move, since it looks passive and the pawn takes away a square from the knight. Advancing the f-pawn two squares seems to be better—this was played by Gukesh in his game against Nakamura. In all other games 1.e4 was tried. 1... f7f5 Black takes the chance to gain some space and create a pawn formation that allows for freer development. 2. d2d4  2... d7d6  3. e1d3  3... e8f6  4. h1g3  4... h8g6 Only four moves have been played and White's position is already difficult, something that can only happen at this level in a freestyle game. Carlsen has problems finishing his development: If e2-e4 is played, then he loses castling rights after the pawn exchange and a check on g4 (although he will allow this later). I thought of 5.Qf2 to castle on the kingside, but then the plan of a6 or a5 followed by Ba7 is unpleasant. Another plan is to develop the bishop to a2 (Carlsen's attempt) or c2 (with 5.c3). 5. a2a4  5... a7a5  6. e2e4 A very risky move. 6... f5e4  7. f3e4  7... b8a7 