Australian star forward David Williams scored a brilliant hat-trick under pressure as ATK Mohun Bagan survived some anxious moments to down Abahani Limited Dhaka 3-1 and make the AFC Cup main round on Tuesday. The Mario Lemos-coached side kept threatening, even as ATKMB's Colaco and substitute Kiyan Nassiri missed two easy chances. ATKMB thus joined Gokulam Kerala, Bashundhara Kings and …