text: Lewis, 19, signed a three-year contract with the English Premier League club on Friday, having played three FA Cup games for them last season.
  Manager Ray McKinnon has also given a contract to Deniz Mehmet following his departure from Port Vale.
  Hibernian midfielder Sam Stanton has also made the move to United on a one-year loan deal.
  The arrivals come with Cammy Bell, last season's first-choice goalkeeper, possibly leaving Tannadice to return to Kilmarnock.
  Bell, 30, is believed to be keen on a move to the Scottish Premiership club.
  McKinnon said of Lewis: "I expect him to challenge for the starting position.
  "Harry comes here as one of the top young goalkeeping prospects in English football.
  "It says so much about his ambition and desire that he has chosen to come up to Scotland to get first-team involvement.
  "It is a coup for us to bring him to Tannadice and I am positive we will hear much more about him during his career."
  Lewis, who has represented England at youth level, joined Southampton from hometown club Shrewsbury Town in 2015, hopes to challenge for starts with the Scottish Championship club.
  "I am excited at the prospect of being involved in first-team football," he told United's website.
  "I believe I am joining a winning team that will be challenging at the top of the league and want to play my part in helping the club secure the title."
  Stanton becomes United's ninth summer signing and their fourth of the week.
  The 24-year-old Mehmet returns to Scottish football after having played with Falkirk before joining Port Vale in January.
  Dutch midfielder Jordie Briels also signed on a one-year contract after the 25-year-old left Fortuna Sittard in his homeland.
target: Dundee United have signed their second goalkeeper in a week by bringing in Harry Lewis on loan from Southampton.