Oxford 1 Pompey 2
Patrick Agyemang and John Marquis were on target as Pompey won at Oxford to progress to the area quarter-finals of the Johnstone’s Paint Trophy.
The Blues were well below par in the first half and Oxford wasted a couple of decent opportunities to punish them.
Pompey were not quite so forgiving, however, and Agyemang came off the bench to net an impressive opener.
Marquis then made amends for a couple of earlier misses by heading home to secure the visitors’ passage into the next round, despite James Constable's late reply.
Guy Whittingham made three changes from the side that beat Rochdale in the league at the weekend.
Gavin Mahon made his debut alongside Romain Padovani in midfield, while Yassin Moutaouakil returned from a three-match ban at right-back.
The early stages took place almost entirely in Pompey’s half, but there were no chances to liven up a low-key atmosphere.
That changed on 15 minutes when Constable tried to sweep home a cross from ex-Blues youngster Ryan Williams, only to be denied by a fine Trevor Carson save.
The visitors were then dealt a blow when Marcos Painter, who had picked up an injury a few minutes earlier, limped off and was replaced by Shaun Cooper.
Oxford defender Michael Raynes probably should have broken the deadlock on 28 minutes when he was left alone to meet David Hunt’s corner, but could only guide the ball wide of the post.
Josh Ruffels then curled a shot narrowly over the bar from the edge of the box after Johnny Ertl’s pass had been intercepted.
Home keeper Ryan Clarke, meanwhile, was a virtual spectator at the other end as Pompey struggled to find any fluidity going forward.
Half Time: Oxford 0 Pompey 0
The visitors' first decent chance arrived five minutes into the second half after Raynes had conceded a free-kick wide on the left.
Ricky Holmes sent a decent cross into the box, but the ball was headed clear before Mahon could reach it.
Clarke was then called into action for the first time, although the keeper was not overly bothered by Padovani’s tame effort.
Whittingham made an attacking change on the hour mark, bringing on Agyemang for Padovani.
But it was Oxford who went close to breaking the deadlock moments later, with two chances in quick succession.
First Carson saved well after Constable had met O’Dowda’s cross and then, after the striker had sent the ball across the face of goal, Moutaouakil did well to clear from the line.
The second half was certainly proving to be more open than the first and Marquis was not too far away with a dipping volley from outside the area.
And Pompey opened the scoring on 65 minutes thanks to a fantastic finish from AGYEMANG.
The striker picked up the ball wide on the right, cut inside and curled a shot into the bottom corner with the outside of his right foot.
Clarke then did well to stop the Blues from doubling their advantage, getting down low to his left to palm clear Holmes’ drive and then recovering to prevent Agyemang from cutting the loose ball back to Marquis.
Marquis had a great opportunity on 77 minutes, but was unable to connect with the ball after Agyemang had flicked on Moutaouakil’s throw.
The striker got himself into a great position again soon after when he charged down Asa Hall’s clearance. This time, however, he fired into the side netting with just the keeper to beat.
Still Pompey kept pressing forward and Jed Wallace was next to try his luck, jabbing a shot towards the top corner that forced Clarke to stick out a hand and push clear.
But the Blues did strengthen their position on 82 minutes when MARQUIS met Moutaoutakil’s cross and glanced a header into the bottom corner.
Constable slammed home a consolation goal late on, but Pompey held on to make it back-to-back victories and book their place in Saturday’s area quarter-final draw.
Oxford (4-2-3-1): Clarke; Hunt, Raynes, Mullins (c), Newey; Davies, Ruffels; Williams (Hall 72), Potter (Smalley 42), O’Dowda; Constable
Goals: Constable 89
Booked: Raynes, Smalley, O’Dowda
Subs not used: Crocombe, Bevans, Rose
Pompey (4-2-3-1): Carson; Moutaouakil, N’Gala, Bradley, Painter (Cooper 17); Mahon, Ertl (c); Wallace, Padovani (Agyemang 60), Holmes (Barcham 78); Marquis
Goals: Agyemang 65, Marquis 82
Booked: Marquis, Wallace
Subs not used: Smith, Whatmough
Referee: Iain Williamson
Attendance: 3,697 (1,132 Pompey fans)