Petrov's Defense: Classical Attack, Mason-Showalter Variation

1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Nc6

The Petrov's Defense: Classical Attack, Mason-Showalter Variation is a chess opening classified as ECO C42, reached after 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Nc6. It is a line of the Petrov's Defense. White is to move. 2 named lines continue from this position.

In 12.6 million rated Lichess games (blitz and slower), this position was reached 307 times by this move order. White won 45%, 9% were drawn and Black won 46%. The most popular continuation is 7. O-O (78% of games).

Engine evaluation: +0.26 (Stockfish, depth 49; best line 7. O-O Be7 8. c3 Bg4 9. Nbd2 Nxd2)

ECO: C42
Moves: 12 plies
FEN: r1bqkb1r/ppp2ppp/2n5/3p4/3Pn3/3B1N2/PPP2PPP/RNBQK2R w KQkq - 2 7
PGN: 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Nc6

Analyse with Stockfish · Board image (SVG) · Open on Lichess

Results by rating

Average rating	Games	White / draw / Black
0-1499	13	54%38%
1500-1999	111	49%45%
2000+	183	43%46%
All	307	45%46%

Most played moves

Move	Games	White / draw / Black
7. O-O	239 (78%)	49%44%
7. c3	22 (7%)	27%23%50%
7. c4	12 (4%)	25%25%50%
7. h3	10 (3%)	40%20%40%
7. Nbd2	6 (2%)	17%83%
7. Qe2	6 (2%)	50%50%
7. Nc3	4 (1%)	50%50%
7. a3	4 (1%)	50%25%25%

Master games

897 over-the-board games are classified under this line (White 40%, draw 41%, Black 19%). The strongest:

LCZero 0.31-dag-c93c6a8-BT4-61 (3652) – Stockfish dev-20250118-8e3e22b (3683) 1/2-1/2 · TCEC 27 Theory Bonus · 2025-01-22
Stockfish dev-20250118-8e3e22b (3683) – LCZero 0.31-dag-c93c6a8-BT4-61 (3652) 1/2-1/2 · TCEC 27 Theory Bonus · 2025-01-22
GM Fabiano Caruana (2786) – GM Ian Nepomniachtchi (2773) 1/2-1/2 · Superbet Classic 2022 · 2022-05-11
GM Sergey Karjakin (2753) – GM Shakhriyar Mamedyarov (2804) 1/2-1/2 · 80th Tata Steel GpA · 2018-01-16
GM Vladimir Kramnik (2808) – GM Li Chao2 (2746) 1/2-1/2 · 10th Tal Mem 2016 · 2016-09-27

Search all games of the Petrov's Defense: Classical Attack, Mason-Showalter Variation and its sub-variations

Highest-rated Lichess games

behrooz10000 (2619) – IM MrSuccess (2623) 0-1 · 2026-09-05 · 180 + 2s
atsaynm (2639) – pop-up (2551) 0-1 · 2026-09-03 · 180 + 0s
Nodrawww (2524) – ORNESAN (2579) 0-1 · 2026-09-01 · 180 + 0s

Comes from

Petrov's Defense: Classical Attack 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4

Continuations

Petrov's Defense: Classical Attack, Jaenisch Variation C42 · 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Nc6 7. O-O Be7 8. c4
Petrov's Defense: Classical Attack, Krause Variation C42 · 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Nc6 7. O-O Be7 8. Re1 Bg4 9. c3 f5 10. c4

More Petrov's Defense lines (all)

Opening names and moves from the Lichess openings dataset; statistics from the Lichess open database, 2026-09 (CC0), sample of 12.6 million games, bots excluded; evaluations from Lichess cloud analysis (all CC0). Master games from The Week in Chess #920–#1664 by Mark Crowther, used with permission.