With bears continuing to maintain a strong grip on the market, oil prices remaining elevated, and investors exercising caution ahead of the US Federal Reserve's policy outcome, the sustainability of the previous day's uptrend will be key to watch in the F&O expiry session on October 27. The 22,500–22,400 range is expected to act as an immediate support zone for the Nifty 50. A break below this zone could trigger a further decline towards 22,200.