411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Bb4/3. Nxe5/3...Nc6/4. Nf3/4...f5
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
not chess opening theory
4...f5 — Rayford Gambit Declined: Mikeś Gambit
4...f5 immediately challenges White's e4-pawn and tries to open the f-file for Black's attack. It also gives Black a way to gain activity instead of immediately trying to recover the e5-pawn.
5. exf5 accepts the challenge and wins the f5-pawn, but opens lines around White's king and black can get it back by 5... d5 or 5... d6.
Downsides: The main drawback of 4...f5 is that Black weakens the kingside and moves another pawn before completing development. White can also challenge the f5-pawn and use the extra material to maintain an advantage.
An independent line is 1. e4 e5 2. Nf3 Bb4 3. Nxe5 Nc6 4. Nf3 f5 5. exf5 d5! (or d6).
The Rayford Gambit Declined – Mikeś Gambit is characterized by 1. e4 e5 2. Nf3 Bb4 3. Nxe5 Nc6 4. Nf3 f5.