17 Rb7!!, when 17...Bxb7 loses to 18 Qe6+ Kc7 19 Bxe5, 17...Bxf4 18 Qxf6+!! exf6 19 Ne4# is a cute mate, and after 17...Bd7! 18 Bg3, 18...Rf8 is no longer possible due to 19 Qxh7!! with the same theme of the mate on e4 (Qxf6 fails this time to ...exf6 and ...Ke7).