Goals from Sam McQueen and Olufela Olomola sealed the win for Martin Hunter’s men against the League 2 outfit.



The result leaves Saints on four points and second in the group, two behind Crawley Town, who they face in their final group game in November at St Mary’s.



Hunter was able to call upon Harrison Reed, Jake Hesketh and McQueen for the game, while Olomola started after being named on the bench for the first team against Hapoel Be’er Sheva and Leicester City.



Saints had impressed in their cup opener against Charlton in August, and they started on the front foot in Essex.



The opening goal came after just eight minutes, as McQueen headed Thomas O’Connor’s corner home at the near post. It was the defender’s second goal against the U’s, having scored while on loan at Southend United last season.



The goal seemed to wake the hosts up, as Denny Johnstone went close shortly before they found the equaliser. It was Johnstone’s pass that created the goal, as he found Dion Sembie-Ferris, who applied the finish from a tight angle.



As the game edged towards half time, Saints went within a few inches of regaining the lead.



Olomola closed down opposing goalkeeper James Bransgrove and the ball broke kindly for Tyreke Johnson, but the winger was unfortunate to see his effort from long range drift just wide of the far post.



Just as they had in the opening period, it was Saints who made the brightest start following the interval.



They were rewarded for their efforts with 51 minutes on the clock, as Josh Sims did brilliantly down the right to cross for Olomola, who applied a powerful finish from six yards.



The striker’s goal capped an excellent week for the youngster, having been named on the bench for the draws with Hapoel Be’er Sheva and Leicester City.



The hosts introduced striker Chris Porter in the hope of finding an equaliser, and with 18 minutes remaining it looked like he would do just that. But Alfie Jones produced a brilliant defensive block to keep Saints ahead.



Hunter's side then went close to doubling their lead, as Johnson was found by Olomola, but Colchester goalkeeper Bransgrove made a smart save low down to his right.



There would be no late drama for Saints, as they held on to make it four points from their opening two games.

Colchester United 29 James Bransgrove (GK) 5 Luke Prosser (C) yellow card 7 Drey Wright replace Cameron James (74′) 10 Sammie Szmodics 12 Kane Vincent-Young 14 Alex Wynter 17 Denny Johnstone replace Chris Porter (64′) 21 Dion Sembie-Ferris goal replace Tariq Issa (46′) 24 Craig Slater 32 Glen Kamara 33 Lewis Kinsella yellow card Substitutes 25 Dillon Barnes 9 Chris Porter 16 Femi Akinwande 18 Tom Eastman 35 Cameron James 38 Chris Regis 46 Tariq Issa Southampton 41 Harry Lewis (GK) 18 Harrison Reed (C) 32 Olufela Olomola yellow card goal 35 Alfie Jones 38 Sam McQueen yellow card goal 39 Josh Sims 42 Jake Hesketh 43 Yan Valery 48 Ollie Cook 49 Thomas O'Connor 51 Tyreke Johnson Substitutes 56 Adam Parkes 47 Richard Bakary 54 Siph Mdlalose 55 Callum Slattery 57 Jake Vokins 58 Aaron O'Driscoll 59 Jonathan Afolabi