The hosts raced into a two-goal lead early on, before Smalling's header sparked the response, with Wayne Rooney's stunning effort and an own goal from former Reds defender James Chester eventually securing the win.
United centre-back Smalling was delighted to get his name on the scoresheet, and believes the victory could give his side a boost in the title race. He told MUTV: "It was great [for me] to chip in [with a goal], and I think it gave us some real momentum.
"Wayne [Rooney] has been putting in some great crosses from these set pieces and he came up with the second goal himself.
"I think it’s going to be a pivotal three points and it keeps us on this run as well, which is important because it is difficult when you have to play again two days later. It’s always easier when you go into a game off the back of a win.
"We had belief going into this game, and after this win we’ll continue to pick it up. I think we've had our setbacks this season, we need to make sure that we don’t have any more and that we keep winning."
As for the game itself, the defender was critical of the way United began the game, but praised the fighting spirit