However, Southampton failed to make the most of their superiority and were eventually punished when Van Persie struck the winning goal with a little under 20 minutes remaining.
Here, Sports Mole takes an in-depth look at whether United were worthy of a win that takes them up to third in the table.
On target: 4
On target: 2
Was the result fair?
No. Southampton will be wondering exactly how they are not celebrating a win right now as they had by far the better of this match for long periods. They outplayed United in almost every area of the field for the vast majority of the game, but just lacked that killer instinct in the final third.
The statistics speak volumes about this match, and they are not misleading when it comes to Southampton's level of dominance. United only manufactured one real chance of their own, and even that came from a set piece as Van Persie squeezed home the winner. Their other goal, and indeed their only other shot on target, came from a defensive error.
The hosts had the chances to win this match fairly comfortably, and even a draw would have been less than they deserved. To have lost this game will hurt Ronald Koeman, while his compatriot Louis van Gaal will know that his side have got away with one tonight. The Saints deserved all three points, but instead they are leaving with nothing.
Putting the disappointment of the result to one side for a second, Koeman must be delighted with how his team played this evening. They looked like a different side to the one that was beaten convincingly by Manchester City in their last home match, and more like the team that began the season so impressively.
They pressed really well off the ball and were always eager to get forward and attack the United defence. They looked like they wanted the win more than United, and the only reason they haven't come away with the points today is their failure to capitalise on their dominance. They lacked a crucial bit of quality in the final third at times, with Shane Long in particular guilty of missing a couple of clear chances.
The result is ultimately the most important thing, however, and it is now three defeats in a row for the Saints. They have dropped out of the top four as a result, and their Champions League hopes have certainly been dented by this recent slump. Performance-wise, they were very good today, but they must do better in terms of results if they are to mix it with the big boys.
Man Utd's performance
They say it is important to play badly and still be able to win, and that is exactly what United did this evening. Van Gaal certainly won't want many repeat performances of this game, though, as they would lose more than they win if they were to play like this every week.
It wasn't far short of shambolic from United in the first half as they were continually overrun by Southampton's midfield and attack. Van Gaal tried to change things by taking off the struggling Paddy McNair after just 39 minutes, but it was only when Van Persie got his second goal that they really began to stem the tide. Their passing was poor and they struggled to cope with Southampton's intensity and pressing throughout
They will know that they had to ride their luck to get this result, but at the end of the day it is another three points and a fifth straight win. They are up to third in the table and comfortably clear of the likes of Arsenal, Liverpool, Tottenham Hotspur and Everton, so that Champions League spot is looking very likely right now.
Sports Mole's man of the match
Robin van Persie: There were a host of other players more involved in the match than Van Persie this evening, but it was he who made the biggest difference. He took both of his goals well and had United's only other shot of the match too, lashing an effort into the side-netting shortly before half time. All of the talk before the game was to do with the two managers, but it was the Dutchman on the field that had the deciding say tonight.
Van Persie was given a big helping hand on his way to that man of the match award, with Fonte gifting him an early Christmas present for the opening goal. The Southampton skipper took a big enough risk playing a blind back-pass, but he also failed to put enough on it, allowing Van Persie to nip in and poke his side ahead.
Kevin Friend's biggest decisions didn't arrive until the closing minutes, when both Sadio Mane and Marouane Fellaini made challenges that could have resulted in red cards on another day. Mane picked up a yellow and Fellaini escaped unpunished on an otherwise uneventful evening for the official.
Southampton: Southampton will be looking for an overdue return to winning ways when they take on Burnley at Turf Moor on Saturday.
Man Utd: United, meanwhile, face arguably their biggest match of the season on Sunday as they host fierce rivals Liverpool at Old Trafford. body check tags ::