Jose Mourinho has revealed that Manchester United are prepared to do business in the January transfer window should a "fantastic opportunity" come along.
The Portuguese previously claimed that the Red Devils would not be making any major deals this month, preferring instead to wait until the summer.
However, United have been heavily linked with Alexis Sanchez, who is rumoured to be on the verge of departing Arsenal just a few months prior to the expiry of his contract.
Sanchez was absent from the Gunners' matchday squad which fell to a 2-1 defeat at Bournemouth, and Arsene Wenger has revealed that the Chilean's future will be decided in the next 48 hours.
"Our squad was not [built] to have new players in January," Mourinho told Sky Sports News ahead of United's Premier League meeting with Stoke City on Monday night.
"We build a squad with this idea, with this philosophy that I share with Mr [Ed] Woodward and the owners. Normally the investment is to be made in the summer. The balance of the squad is made in the summer.
"But sometimes, it [a transfer] can happen. Okay, if on the table is a fantastic opportunity, you fight for that fantastic opportunity. If it happens, it happens. If it doesn't happen, it doesn't happen. But I like my squad and I like my players."
Manchester City and Liverpool have also been linked with Sanchez.