The Red Devils take on the Portuguese side knowing a victory will not only see them qualify for the knock-out stages of the Champions League, but will likely secure their place as Group H winners.
Smalling, who missed out on representing England at Euro 2012 thanks to injury, has not played a competitive match since May 6, and is yet to feature this season since breaking a bone in his foot during pre-season training back in July.
Sir Alex also revealed that Phil Jones should be back soon, and begins training next week with the rest of the team.
"Phil Jones starts training next Monday on the football side with us," Sir Alex told reporters. "He's making really good progress.
|GROUP H PREVIEW
|9/4||Manchester United are 9/4 with William Hill to claim a point at Braga
"Those two young players are outstanding young defenders and it'll give us a fantastic squad; the complete squad to mount all our challenges. We've done well so far, but I think we can be stronger as a unit with players like Smalling and Jones back."Two players Ferguson will not have at his disposal in Portugal, however, are Darren Fletcher and Paul Scholes, after both midfielders were left behind in Manchester when the squad flew out on Tuesday.
Fletcher is suffering with illness, while Scholes, who hasn't featured in any of United's last four fixtures, is being rested.
"Fletcher got a little bit of a cold on Sunday, and there’s no point taking him travelling with a cold," Sir Alex added.
"Scholesy, for the last few games I've been resting him to freshen him up a little bit. I'm just taking care of an old man, that’s all!"