Victory would take United above the Saints into third place in the table and cement Louis van Gaal's side's claims to a Champions League place.
United have seen off Crystal Palace, Arsenal, Hull and Stoke within the last month, while Liverpool lie in wait next weekend.
Young told the club's website: "Southampton have started the season very well and are third in the league, so we know it is going to be tough
But if we can go there and produce displays like we have shown, especially in the last four matches, then I'm sure we can get the three points.
"When you are winning games then confidence is always sky high
When you have been on a run of wins - both at home and away - then it is fantastic for confidence.
"Everybody is pulling in the right direction and feeling good and we will take that into the game against Southampton
It is going to be a big game and there are definitely no easy games in the Premier League."
United's form has convinced Van Gaal that some silverware is within their grasp this season and he has pinpointed the FA Cup as a trophy to mount a real challenge to win.
Van Gaal told MUTV: "I always want to win a a trophy
It's something I've done in my first season at other clubs, so I want to give the fans a title
The easiest way to win silverware is in a competition like the FA Cup, which requires fewer matches to win."
Van Gaal will cross swords with fellow Dutchman and his former assistant Ronald Koeman on Monday - but both managers have declared their personal relationship to be "private".
Koeman, now Southampton manager, worked under van Gaal at Barcelona but fell out when they were at Ajax in 2004, when Koeman was coach and Van Gaal the technical director.
Van Gaal described Koeman as "a very good coach" but refused to talk about their relationship since the fall-out.
The United manager added: "I don't have to describe my relationship with the trainer of the opponent..
that's more private."
Wayne Rooney will be fit to face Southampton - the United skipper had a scan on Thursday to examine a possible knee problem but was given the all-clear.
However record signing Angel di Maria will not be ready to return from his injury in time for the trip to the south coast
Luke Shaw (ankle), Jonny Evans (ankle), Rafael (groin), Daley Blind (knee) and Phil Jones (calf) are all expected to miss out.
Source : PA
Source: PA