Sir Alex Ferguson’s side needed to beat the Gunners in order to maintain pressure on Manchester City, who earlier in the day had beaten Tottenham to temporarily move six points clear at the top.
United's task wasn't helped by injuries to Phil Jones and Nani, while Wayne Rooney, Michael Carrick and Patrice Evra all played through the pain barrier after sustaining individual knocks.
The Reds rallied though and managed to record a priceless victory over Arsene Wenger’s side with goals from Antonio Valencia and Danny Welbeck outweighing Robin Van Persie’s repost.
“It was another tough game,” Smalling told MUTV. “We were always going to get that but I thought we showed good character to get the late winner.
“We played some great football; Antonio and Nani were causing mayhem for their full-backs. We couldn’t quite keep it up for the duration of the second half but we had our spells and made it count.
“It does show our togetherness. Even when it was 1-1, they had the advantage but we came out victorious even though we took a few more knocks.
“I think we’ve taken enough knocks for the whole league," joked Smalling in reference to United's seemingly never-ending spate of injuries.
"But we have shown our togetherness and if we can keep ticking off these wins then we’ll be in a good position.”