By Sedara Oluwadara Brighton survived a late onslaught to secure a first win at Old Trafford and condemn Erik ten Hag to a losing start as Manchester United manager.   Pascal Gross' first-half double stunned the home supporters, who were desperate to see their team put a miserable end to last season behind them.     However, United were totally outplayed in that opening period by Graham Potter's side, who beat them 4-0 at the Amex Stadium in May on their way to a ninth-placed finish, their highest in history.   Not even the second-half introduction of Cristiano Ronaldo