Financial rules around Sporting mean they have to confirm to the Lisbon Stock Exchange when an agreement has been reached for him to leave.
Amorim is due to speak to the media at 13:00 before Friday’s Estrela match.
Three hours later, Ruud van Nistelrooy will conduct his first news conference since being appointed as United’s interim manager.
After the victory over Leicester, Van Nistelrooy said he was willing to continue working at the club “in any capacity”.
United have home league matches against Chelsea on Sunday and Leicester on 10 November before the international break, split by a Europa League tie with Greek side PAOK at Old Trafford on 7 November.
They head to newly promoted Ipswich, managed by former United coach Kieran McKenna, immediately after the international break.
Norwegian side Bodo/Glimt could be Amorim’s first Old Trafford opposition in the Europa League on 28 November, with a Premier League game against Everton the following weekend.