A very special Najdorf
When White wants to tackle the Sicilian Najdorf Variation — 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 — very directly, 6.Bg5 is a popular choice. After 6...e6 7.f4 the rare 7...b5, the Polugaevsky Variation, leads to sharp and difficult positions. Petra Papp brings the theory of this variation up to date in her article for ChessBase Magazine #207, explaining typical strategies and motifs for both sides.
Source: chessbase.com