Second half goals end semi-final hopes.
Colchester United's remarkable journey in this year's Premier League Cup came to an end on Monday night.
Two second half goals from Portsmouth were enough for the U's fellow League Two side to progress to the semi-finals.
In an evenly contested first half, the two teams traded chances and Eoin McKeown had a good opportunity from out wide that forced Liam O'Brien into a decent stop.
The U's then had a great chance to take the lead as they were awarded a penalty on 38 minutes.
However, O'Brien turned away Tariq Issa's spot kick after the U's midfielder had been fouled in the box.
That miss proved costly as the home side took the lead early in the second half.
Oxlade-Chamberlain headed on for the dangerous Kabamba to race onto and slide past Barnes to break the deadlock.
The U's responded well to that setback, pressing Portsmouth back in the search of the equaliser.
The game remained in the balance until five minutes from time as Jamal Lowe sealed the victory for Pompey.
He won the ball in the heart of midfield, pushed forward and smashed home an unstoppable shot past Barnes.
Colchester: Barnes, Vincent-Young (Brown 46), Peter (c), Kensdale, Kinsella, Diaz Wright, Edge, Howard, Issa, Dunne (Jones 81), McKeown
Subs not used: Wilson, Keys
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