I have not yet seen all the responses to this suggestion that the 2. ... Rd3+ line is better.  Having seen the outcome of the 2. ... Rb4  in the daily puzzle line, I must agree.  White has a difficult task forcing mate with Queen, King, and a-pawn vs Rook, King and c-pawn.  White's problem is, the three black pieces protect each other -  the Queen cannot capture the rook when the king is on an adjacent square.  However, with occasional checks and occasional situations where black must move and abandon his strongest defensive position,  I think white can maneuver his king to where he can protect the queen when the queen captures the rook adjacent to the black king.  In short, I think white can still force a win.