Paul Pogba had a late penalty saved by Southampton's Angus Gunn, but Romelu Lukaku had no desire to try and seal his hat-trick.
Romelu Lukaku said he never intended to try and take a late penalty for Manchester United that would have given him a hat-trick against Southampton, after Paul Pogba missed the effort.
Lukaku's brace had put United 3-2 up at Old Trafford on Saturday, with Ralph Hasenhuttl's men having struck through Yan Valery and James Ward-Prowse.
But when Marcus Rashford was fouled by Stuart Armstrong in added time, it did not cross Lukaku's mind to try and wrestle the ball from team-mate Pogba.
Angus Gunn saved Pogba's penalty, the France international failing to convert from 12 yards for the third time in the Premier League this season.
"I am a striker and I wanted Paul Pogba to score the penalty," Lukaku said.
"He has been on a good run but he has been an important player for us and will bounce back.
"I was focused on the win and help my team-mates. The manager [Ole Gunnar Solskjaer] gave me another chance today.
"We have to look one game at a time and are working hard on the training ground. We are ready for the challenge."
Solskjaer's side remain unbeaten domestically since he replaced Jose Mourinho, with United moving above Arsenal into fourth place.
"We knew we had to win the game today and did it," Lukaku added. "Not our best game but we have to be happy.
"We created a lot of chances in the opening 10 minutes but won the game."