FOREX-Dollar on solid ground ahead of Fed

* Dollar index up 2.2% this month; +0.2% in Asia session * Yen eyes 4.5% monthly drop * Fed focus on likelihood of March cut (Updates prices) By Tom Westbrook SINGAPORE, Jan 31 (Reuters) – The dollar headed for its biggest monthly gain since September and the yen for its sharpest drop in over a year on Wednesday, as traders waited on a U.S. rates decision to round out January. A sharp slowdown in Australian inflation pushed the Aussie dollar down 0.5% to $0.6567 and rallied bonds as investors pulled forward wagers on interest rate cuts. Elsewhere moves were more modest, and the yen made little immediate reaction to a hawkish tilt at the Bank of Japan, while markets waited to hear from the Federal Reserve.