Smalling says even just hearing the Champions League music brings it home to him that United are missing out Europe's elite club competition.
United, however, are on course to qualify for the next season's Champions League, with four successive victories propelling Louis van Gaal's side to fourth place in the Premier League table
Three points from the trip to Southampton on Monday night and United will leapfrog Saints into third place.
Smalling said the bitter experience of being a bystander in European football is all the incentive his United team-mates need.
"You hear the Champions League music when they all line up and it's just a case where we've been in it year after year, so it's a sad time," Smalling told www.manutd.com
"We'll be making sure we don't miss out again next time.
"I was watching it the other week
Even when we were in it, I would watch it on the other night anyway
Even more so this year
It's a bit gutting that we're not involved but you can see the standard of football we need to make sure we rise to."
United's four victories have been achieved despite a lengthy injury list, not least in defence, but they will at least have captain Wayne Rooney available after a scare last week which saw the England striker have a scan on a possible knee problem.
It may also be a good time to play Ronald Koeman's Saints, whose impressive start to the season has stalled with successive defeats in their last two games.
United boss Van Gaal, meanwhile, has spoken of being impressed at the team spirit that has developed, highlighted by the Christmas party organised last week by Rooney.
"It was fantastic," Van Gaal told MUTV
"Usually, I don't use words like this, but I think it showed the cohesion in our group from both the players and staff
My wife and I enjoyed it very much.
"The squad is very important, and that's why the timing of our Christmas party was fantastic - it showed the togetherness in the squad
I think we are in a good position."
The match at St Mary's is being built up as a battle between warring Dutch coaches Van Gaal and Koeman, who fell out when they worked together at Ajax in 2004
The pair have refused to discuss their relationship but they appear to have buried the hatchet.
According to Dutch newspaper De Telegraaf, at a recent League Managers' Association meeting Van Gaal complimented Koeman on his work, told him: "You have a good team," and clapped him on the shoulder.
Source : PA
Source: PA