Chess Opening Theory/1. e4/1...b6/2. d4/2...Bb7/3. Bd3/3...f5/4. exf5

= Matovinsky Gambit Accepted =

4. exf5
Accepting the gambit by taking black's f-pawn. Black can now play:
 * 4...Bxg2, capturing white's unprotected g-pawn, and threatening white's cornered rook

Theory table
'''1.e4 b6 2. d4 Bb7 3. Bd3 f5 4. exf5'''