[Event "?"]  [Site "?"]  [Date "2017.06.17"]  [Round "?"]  [White "Tactics #58"]  [Black "   Raymond Keene - Erling Mortensen, Aarhus 1983   "]  [Result "*"]  [SetUp "1"]  [FEN "8/p2Rp1r1/r2p4/P1p2p2/2P1k3/1P2P1P1/4KP2/R7 w - - 0 1"]  [PlyCount "7"]   1. b4 {[pgndiagram] The first step. Due to the threat of b5, White forces  Black to take with the c-pawn, freeing the d4 square}   (1. f4 {Also wins though}  Rh7 2. Rh1 {And Black has to part with a rook}   (2. Rxe7+ Rxe7 {[pgndiagram]  Now doesn't work, because d4 is unavailable to White})) 1... cxb4 2. f4 Rc6 {  [pgndiagram]}   (2... Rh7 3. Rxe7+ Rxe7 4. Rd1 {[pgndiagram] And the point of b4  is now revealed. White mates on d4 on the next move}) 3. Rd1 Rxc4 4. Rc7 {  [pgndiagram] And White wins.} *