Saints have handed United States Under-20 goalkeeper Cody Cropper a two-year professional contract following a successful trial.
The 19-year-old has spent much of the past two months with Martin Hunter's Under 21 squad, playing in a number of their pre-season friendlies.
He kept his place in goal for their first game of the Barclays U21 Premier League season, playing in their win over Sunderland on 20th August.
Cropper spent the previous two seasons with npower Championship outfit Ipswich Town, where he made the first team's substitutes bench on three occasions.
However, after being released at the end of the 2011-12 campaign, he was picked up by Saints and today put pen-to-paper on a permanent contract with the Club.