The Baggies were 2-0 victors against Peterborough on Boxing Day, but it needed a half-time rant from Di Matteo to get the players going after a forgettable opening 45 minutes at The Hawthorns.
“I had to raise my voice a bit because I disagreed with how we played, when it is needed I can do that,” said the Italian, who was in charge of the MK Dons side defeated by the Iron in the League One play-offs last season.
“We did increase the tempo in the second-half and deserved to win. If we can now beat Scunthorpe on Monday we can end the first half of the season with a nice cushion of points.”
United will be without defedner Cliff Byrne, who is suspended after being sent off at Middlesbrough on Saturday. Andrew Wright will expect to deputise.
Gary Hooper, the Iron's top scorer, will be given as long as possible to recover from an ankle injury. Several first-team players are struggling with an illness, with Josh Lillis considered a doubt as a result.
Di Matteo's side are without left-back Joe Mattock, who is absent after collecting his fifth booking of the season against Peterborough. Scott Carson, the Baggies' first-choice keeper, concludes a three-match suspension.
The winger Jerome Thomas is expected to feature despite suffering from flu and a hamstring strain. Centre-back Abdoulaye Meite will play his final game before joining the Ivory Coast squad for the African Cup of Nations.