OXFORD United remain pointless in Sky Bet League One after they were swept aside by Portsmouth at Fratton Park.

The only surprise was it took the visitors until the second half to make their dominance pay.

United had ground their way through the first half, which stayed stubbornly goalless thanks to Pompey’s lack of cutting edge and Jonathan Mitchell’s excellent penalty save.

But Gareth Evans made up for his spot-kick woe to open the scoring three minutes into the second half.

It opened the floodgates and Pompey quickly stretched their lead via a Rob Dickie own goal and a close-range finish from the impressive Jamal Lowe.

Belatedly United, who had offered next to nothing going forward in the opening hour of the game, threatened in the closing stages.

Substitutes James Henry and Jon Obika hit the woodwork, before Jack Whatmough’s own goal at least gave them a first league goal of the season.

The addition of six extra minutes led to a roar from the visiting fans, but they were quickly heading for the exit as Lowe curled in a terrific strike for his second goal of the afternoon.

It was the tenth goal United have conceded in three league games and they remain rooted to the foot of the fledgling table ahead of home games with Accrington Stanley and Burton Albion next week.

Rob Hall (knee) and Ricky Holmes (back) were missing for United, which prompted a reshuffle for boss Karl Robinson.

Shandon Baptiste, who impressed in the Carabao Cup win on Tuesday, kept his shirt for a first senior league start.

It was thought he would play alongside debutant Hanson in central midfield, but instead the 20-year-old was used in a No 10 role.

Baptiste was in theory the closest player to Sam Smith, but the striker cut an isolated figure for much of the first half.

After a slow start where Ronan Curtis and Matt Clarke headed over half-chances, Pompey began to turn the screw.

On 25 minutes they appeared to have the breakthrough, when Hanson was caught on the ball by Oli Hawkins and conceded a penalty attempting to make amends.

It was at the same end where Alex Mowatt had struck the woodwork on United’s last visit in March and again the spot-kick was wasted.

This time Evans’s effort was on target, but Mitchell leapt to his left and kept it out with a magnificent save on his first league appearance for more than two years.

In the resulting melee, Curtis smashed a shot just wide from the edge of the box.

If United were hoping the penalty save would change the flow of the game, they were wrong.

The visitors reached half-time without mustering a shot of any kind on goal, on or off target.

Aside from a couple of set pieces which were comfortably cleared, Pompey had little to worry about defensively.

At the other end, United continued to ride their luck. Tom Naylor should have scored from six yards just before the half-hour mark when Evans’s cross ricocheted into his path, but the midfielder mis-kicked.

Much of Pompey’s attacking threat came from their right flank. One low centre from Jamal Lowe nine minutes before the break picked out Evans six yards out, but when he spun and shot Curtis Nelson was on hand to make a goal-saving block.

The pressure saw United collect four bookings before the interval. Alongside Hanson, Cameron Brannagan and Baptiste, referee Lee Swabey also cautioned assistant head coach Shaun Derry, who was irked by a decision which went against Nelson.

United survived one more tense moment before the break, when another cross from the right, this time from Ben Thompson, was completely missed by Hawkins.

The hosts would have been frustrated to go in level, but the goal arrived within three minutes of the restart.

Again the supply line was from the right. Lowe got the better of Garbutt and although his cross was scuffed by Hawkins, the ball rebounded for Evans to drive into the net from eight yards.

If the visitors’ game plan was to frustrate and look to nick something, they now needed a Plan B.

But within eight minutes it was 2-0. From the same flank Lowe whipped in a wicked cross which Dickie felt he had to deal with, but his diving header only sent the ball past Mitchell and into the far corner of his net.

Robinson’s response was to make a triple substitution. One of the fresh players, Henry, almost made an immediate impact, but the midfielder’s header from Tony McMahon’s cross was just wide of the far post.

It was the visitors’ first attempt on goal of any note, in the 63rd minute.

Pompey sensed blood, though, and a third goal in 17 minutes duly arrived. United lost out in two aerial challenges from a corner and Lowe was on hand to flick the ball in from close range to make the points safe.

With the contest over, United went on to have their best spell of the game.

Pompey goalkeeper Craig MacGillivray was finally pressed into action by a Brannagan shot which he tipped over.

United came close in their search for a first league goal of the season, with Henry and fellow substitute Obika hitting the same upright in quick succession.

It looked as though they were going to start a league campaign without scoring in the opening three games for the first time since 2000.

But in the 89th minute the U’s did force a consolation, as Whatmough sliced in McMahon’s cross.

Lowe had the final word, though, crowning an excellent afternoon with a high-quality curling finish into the top corner from 20 yards.

Portsmouth (4-3-3): MacGillivray, Walkes, Clarke, Whatmough, Brown, Naylor, Evans, Thompson, Lowe, Hawkins, Curtis (Wheeler 80).

Unused subs: McGee, Burgess, Pitman, Chaplin, Close, Haunstrup.

Booked: Thompson.

Oxford Utd (4-2-3-1): Mitchell, McMahon, Nelson, Dickie, Garbutt (Ruffels 61), Hanson, Brannagan, Browne, Baptiste (Henry 61), Mackie, Smith (Obika 61).

Unused subs: Shearer, Norman, Ruffels, Mousinho, Whyte, Henry, Obika.

Booked: Hanson, Brannagan, Baptiste.

Referee: Lee Swabey.

Attendance: 18,093 (1,312 visitors).