BTC's price experienced selling pressure over the weekend. After last week's substantial decline from the September 13 peak, price could experience some trapping consolidation action where it moves up and retests some key levels.
The .618 retracement of the early September rally could be retested at 20,160, though it has already been retested since the breakdown and got rejected. The .618 retracement of the entire summer rally (mid-June to mid-August) is around 20,503. Both these could be retested by a whipsaw move into FOMC.
Ultimately, the strongest resistance is the 10-month downtrend line further overhead that lies around 21,160, and that would be another chance to sell into the bounce IF that occurs.