Board Position
An orthodox system alternative to the full Orthodox Defence against the Queen's Gambit. Developed by Emmanuel Lasker (1868-1941), a master of the end-game and world champion from 1894-1921. Board Position
Black advances his king's-side knight to K5(e4) (move 6b, left) rather than develop an Orthodox (qv.) 6..QKt-Q2, so as to fork White's dark bishop and knight and provoke a series of simplifying exchanges (trading off two pairs of minor pieces).
After the ensuing development of queens (move 10, right), White usually concentrates on an attack via the queen's bishop's file. Variations of the defence can also occur by the Kt-K5 advance occurring earlier, or even occurring later (as part of neo-orthodox lines).

Begin or Clear or Groups or see move: 1 d4 d5 2 c4 e6 3 Nc3 Nf6 4 Bg5 Be7 5 e3 0-0 6 Nf3 6..Ne4
(Main:) 7 Bxe7 Qxe7 8 cxd5 Nxc3 9 bxc3 exd5 10 Qb3 Qd6
(Or earlier via:) 5..Ne4 6 Bxe7 Qxe7 7 cxd5 Nxc3 8 bxc3 exd5 9 Nf3 0-0