Entering the tie off the back of consecutive league victories, Saints youngsters now turn their attention to progress in the Premier League Cup, with the club having won the competition in 2014/15.
The U23s share a group with Cardiff City and Blackburn Rovers, with the latter coincidently the side Saints beat in the final at St Mary's in 2015 - in front of 12,000 jubilant fans.
U23s boss, Radhi Jaïdi, previewed the clash: "We want to keep the momentum," he began.
"We've had two great results the last two weeks and hopefully that will continue on Friday. It is a new competition, a cup game, and we need to give ourselves a chance to top the group.
"Being clinical is something we work on on a daily basis with the boys, until we get better.
"We've watched the video and hopefully the boys understood what is required. I'm expecting them to apply it on the pitch."
Despite Watford competing in the division below, and perhaps with the odds in his favour, Jaïdi insists focus and preparation will be unchanged in the lead up to the tie.
The visitors sit in 7th place in their respective league standings (PDL South), having lost their previous two outings.
"It doesn't have any change on our attitude," Jaïdi continued. "Or how we'll approach the game.
"It is at home, and we want the boys to be sending a good message to those watching. It is a game we want to win, and give ourselves a chance to progress to the next stage.
"They will have some individual quality and quality in the midfield area and final third. I'm expecting a good challenge for our defenders."