Stam sprained the medial ligament in his right knee in the warm-up against AZ Alkmaar at the weekend and is likely to miss the next two weeks.
Vermaelen is likely to be out for two months after tearing a ligament in his left ankle in the 3-2 win in Alkmaar on Sunday.
Copyright (c) PA Sport 2007, All Rights Reserved.
Do YOU want to write for GiveMeSport? Get started today by signing-up and submitting an article HERE: https://www.givemesport.com/writeforgms