The trip was the Foxes first away tie of the competition and they put in an impressive display to see off their hosts.
Southampton 0-2 Leicester City
The FA Youth Cup
Fifth Round Proper
7pm, Thursday 5 February 2015
St. Mary's Stadium, Southampton
By Simon Collings
First-half goals from Keenan King and England youngster Layton Ndukwu proved to be enough in the end, as Leicester held out in a nervy finish to the match.
Having already seen off Everton and West Ham United to reach the Fifth Round, Southampton went into Thursday’s tie full of confidence.
However, Saints were behind after just nine minutes when King struck for the visitors.
The forward was quickest to pounce when Ollie Cook could only half clear Ben Chilwell’s cross, composing himself with a touch before slotting the ball home.
Leicester continued to dominate proceedings and they doubled their lead ten minutes before the break.
This time it was Ndukwu’s turn to get in on the act, with the England U17 international turning his marker on the edge of box before powering the ball past Harry Isted in the Saints goal.
Leicester began the second half as they ended the first, with midfielder Marcus Barnes firing the ball into the side-netting after he skipped past a defender.
However as the tie moved into the final 20 minutes Southampton threw all they had at Leicester as the visitors were forced to withstand a barrage of attacks.
First Dan Demkiv saw his rasping shot tipped onto the bar by Foxes goalkeeper Max Smith-Varnham, before Armani Little skimmed the post with his long-range effort.
But Leicester held out to book themselves a place in the last eight and a home tie against local rivals Birmingham City.