Two Knights: 4.d4 exd4 5.Nxd4

Definition

The move-sequence 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. Nxd4 defines one of the main branches of the Two Knights Defense. After White’s pawn thrust 4.d4, Black captures the pawn (4…exd4), and White immediately recaptures with the knight from f3 (5.Nxd4), centralising the piece and reopening the bishop on c1. The resulting tabiya is rich in tactical possibilities and has been studied for more than 150 years.

How It Is Used in Chess

Opening Choice: Players who enjoy open, razor-sharp positions select this line to avoid the heavily analysed main line 4.Ng5.
Center Control: By recapturing with the knight, White maintains a strong grip on e4 & d4 squares and keeps the option of c2–c3, Qe2, and long-term kingside pressure.
Flexible Development: Both sides still have multiple candidate moves (5…Nxe4, 5…Bc5, 5…Bb4+), so the position can transpose to the Lolli Attack, Fritz Variation, or quieter Italian-Game structures.

Strategic Ideas

White
- Rapid development and pressure on f7 via Bc4, Nc3, and Qf3 or Qh5.
- Maintaining a space edge in the centre; often aiming for c2-c3 and cxd4 to create a strong pawn duo.
- Tactical motifs: sacrifices on f7, pins along the a2–g8 diagonal, and Greek Gift themes after Bxf7+.
Black
- Counter-attacking the e4-pawn with 5…Nxe4 or developing quickly with 5…Bc5 to target the d4-knight.
- Breaking in the centre with …d5 if tactics permit, liquidating White’s space advantage.
- Accepting structural weaknesses (e.g., doubled c-pawns after …Bb4+ c3) in exchange for rapid piece play.

Main Continuations from the Tabiya

5…Nxe4 6. O-O d5 7. Bb5 – Modern Lolli / Morphy Line
5…Bc5 – Fritz Variation; both sides castle quickly, and fireworks on f2/f7 are common.
5…Bb4+ 6. c3 – Black tries to disturb White’s queenside; can transpose to Petrosian Variation.

Historical Significance

The line dates back to 19th-century Romantic chess. Players like Adolf Anderssen and Paul Morphy demonstrated dazzling sacrificial attacks here, cementing the opening’s reputation for tactical richness. In modern times, grandmasters such as Fabiano Caruana and Viswanathan Anand have revived the 5…Nxe4 branch, backing it with powerful engine preparation.

Illustrative Game

Short & tactical example:

The game (synthetic for instructional purposes) highlights typical motifs: Black’s early …Nxe4 grab, White’s central build-up, and a decisive attack on the open kingside.

Interesting Facts & Anecdotes

World Champion José Raúl Capablanca reputedly disliked facing 4.d4, considering it “annoyingly safe yet venomous.”
Engines once evaluated 5…Nxe4 as dubious; modern neural-network analysis now ranks it fully playable, flipping decades of theory.
The composer Gioachino Rossini, better known for his operas, played the White side of this line in informal Paris cafés, seeking “operatic” sacrificial finales.

Practical Tips

Memorise forcing tactics after 5…Nxe4. Many games are decided before move 15.
With Black, time your …d5 break precisely; a premature thrust can collapse the centre.
With White, do not rush c2-c3 unless you can recapture with a pawn; the knight on d4 is often your best attacking piece.

Two Knights: 4.d4 exd4 5.Nxd4