James scored his third Premier League goal in four appearances with a fierce, rising right-foot drive after only 10 minutes, and the 21-year-old Wales attacker was the biggest threat for Ole Gunnar Solskjaer’s side.
Saints, however, gained momentum in the second half as a disappointing United side grew increasingly sloppy, and Vestergaard capped a spell of pressure with the equaliser just before the hour.
Che Adams had blazed wide of an open goal and David de Gea had saved superbly from Danny Ings before the giant figure of Vestergaard rose to meet Kevin Danso’s fine cross.
It proved the high point of Danso’s afternoon as he was then sent off for a crude lunge at Scott McTominay when he was already on a yellow card, leaving referee Mike Dean with an easy decision.
United, predictably, laid siege to Southampton’s goal in the closing stages but were kept out as keeper Angus Gunn saved superbly from Marcus Rashford and Mason Greenwood, while both Jesse Lingaard and Ashley Young were just off target.
It leaves the Old Trafford side with only one win from four league games, the opening-day win against Chelsea being followed by draws here and at Wolves and that home defeat by Crystal Palace.
Few tears were shed when Manchester United said their farewells to expensive attacking failures Romelu Lukaku and Alexis Sanchez, departed for Inter Milan permanently and on loan respectively.
It was ironic, then, that a lack of killer touch by those left behind saw United leave St Mary’s with just a point after taking charge of most of the first half and mounting an assault on Southampton’s goal following Danso’s dismissal.
James mixed the dangerous and the erratic after his brilliant goal but looks a real talent, with pace to burn and end product – the same could not be said for the disappointing Rashford.
