[Event "Le verrou"]
[Site "https://lichess.org/study/xOVSnWLR/9R8q59cW"]
[Date "????.??.??"]
[Result "*"]
[Variant "From Position"]
[ECO "?"]
[Opening "?"]
[Annotator "https://lichess.org/@/michel_PR"]
[FEN "r1b2rk1/2p1q1n1/ppPp1b1p/3Pppn1/1P5B/2N3P1/P2NB2P/2RQ1R1K w - - 0 1"]
[SetUp "1"]
[Source "https://lichess.org/study/xOVSnWLR/9R8q59cW"]
[Orientation "white"]
1. a4! { Les Noirs n'ont plus la possibilité d'ouvrir la colonne "a" } *