The manager has had to contend with Smalling and fellow England international Phil Jones being sidelined since the start of the season while Jonny Evans was still recovering from an operation in August and Nemanja Vidic has also undergone surgery.
The Reds defended superbly at Newcastle with each individual member of the back four impressing but Smalling will be looking to earn a place in the line-up, starting with the home fixture against Stoke City following the international break. With Sir Alex full of admiration for Evans and Rio Ferdinand in particular, it will be no easy task for the former Fulham defender to force his way into the side.
"Ferdinand and Evans were magnificent [at Newcastle]," enthused Sir Alex. "Absolutely brilliant. That kind of form definitely gives you a solid base. It gives us a security and enables the midfield players and front players to get on with their jobs. They cleared everything.
"We've got to get consistency in the performances and in the results. Once we get that, we'll get into a rhythm. We've got the squad to deal with all the games, we've got a really good squad. And after the international break, we'll have Chris Smalling back which will be another addition to our squad which is very important."