Mourinho dismissed for touchline antics in Manchester United win at SouthamptonRomelu Lukaku secured Manchester United a hard-fought victory at Southampton as Jose Mourinho's men managed to batten down the hatches after half-time.Seven months on from edging an entertaining EFL Cup final against Saints, United arrived at St Mary's looking to maintain their fine start to the campaign against a team struggling for coherence and goals on home turf.United were made to sweat as Mauricio Pellegrino's men launched wave after wave of attacks in the second period, but Lukaku's first-half goal was enough to secure a 1-0 win, taking his side to a club record-equalling 16 points at this stage of a Premier League season.However, while it may have been a successful trip on the field, things did not go so well off it. Mourinho was sent off in stoppage time by referee Craig Pawson for his antics on the touchline, while in the first half some supporters went against United and Lukaku's plea to stop chanting a song about the striker that Kick It Out have called "offensive and discriminatory".United are understood to be preparing a strong response after the song echoed around the ground following the Belgian striker's eighth goal in as many games for his club, having tucked home after his initial header was denied by Fraser Forster.Mourinho's side had it easy in the first half, but after the break their goal came under siege as Southampton fans were treated to attacking intent that has become all too rare at St Mary's.However, a promising second-half display ended in frustration for the home side - in the first game attended by the Gao family since taking majority control of the south coast club - as United managed to hold on.Pellegrino's men were impressive after the break, although it was hard to look any more toothless than they did in a first half when Nathan Redmond's wayward shot was the best they could muster. As for United, they showed their teeth as patience in possession bore fruit in the 20th minute. Ashley Young, again deployed at left-back, was allowed to switch onto his favoured right foot and cross. Lukaku shrugged off his marker and powered a header that Forster could only push back into his path, allowing him to prod home. The continuation of the striker's fine start to life at United was swiftly followed by a chant relating to his penis that fans had been asked not to sing by club and the player himself, followed by a rendition of "we'll sing what we want". Marcus Rashford fizzed a free-kick just wide as the visitors looked to take grip of a match that they were looking comfortable in, with Lukaku's low cross hacked away by Wesley Hoedt as United stroked the ball around with confidence. Saints returned from the break with renewed impetus, though, and Oriol Romeu directed just wide after a corner fell lto him in the box just six minutes after the restart. David De Gea denied Redmond at his near post as the home side continued brightly, with Shane Long seeing penalty claims against Phil Jones rejected. Forster saved well when Lukaku had an attempt on what was becoming rare attacking forays by United, with Marouane Fellaini clearing a dangerous Romeu header before Redmond attempted a low drive. Romeu dragged a shot across the face of goal from an acute angle 12 minutes from time - swiftly followed by substitute Ander Herrera wasting a glorious chance at the other end. Southampton began to tire as they pushed for an equaliser and in stoppage time play was broken up as referee Pawson sent Mourinho to the stands - a decision that bemused the United boss, who shook hands with Pellegrino and some on the Saints bench before departing.