Pompey made light work of fourth tier champions Leyton Orient to win their first away League One match of the season.

They capitalised on the chances carved out before the break, with Marlon Pack and Colby Bishop meeting Joe Rafferty deliveries to provide a healthy lead.

But it was a totally dominant display in the second half, as an Omar Beckles own-goal made sure the noisy travelling fans would have a jubilant journey home.

And they were left even happier in stoppage-time, when substitute Kusini Yengi won and converted a penalty.

John Mousinho made three changes from the side that drew with Bristol Rovers on the opening day of the season.

Christian Saydee replaced the injured Tom Lowery, while Abu Kamara and Conor Shaughnessy were in for Anthony Scully and Ryley Towler.

Joe Pigott – who spent last term on loan at Fratton Park – was a familiar face leading the line for the hosts.

There was a minute’s applause before kick-off in memory of the late Chris Bart-Williams, who had started his career with the Londoners.

The match itself was slow to click into gear, with neither keeper being tested in a fairly soporific opening.

Pompey looked more comfortable in possession than their opponents and were searching for an end product to much their passing play.

It might have arrived when Bishop swept the ball out to Gavin Whyte on the right and he cut back for Saydee, whose effort was blocked.

But the deadlock was broken moments later, as PACK beat his marker to meet Rafferty’s low corner and hit a shot that struck the inside of the post before crossing the line.

It might have got even better when an excellent long pass from Regan Poole headed towards Bishop, but keeper Sam Howes just about beat him to the ball.

Orient had chances to level before the break, however, and Will Norris got down to deal with a low George Moncur drive.

The same player then tried to benefit when Pigott stopped Shaughnessy seeing the ball out of play, but Poole flung himself bravely in front of the shot.

Pompey were more clinical at the other end and doubled their advantage when another delivery from Rafferty was headed home by BISHOP at close range.

Half Time: Leyton Orient 0 Pompey 2

There was a change for the visitors at the break, with Kamara making way and being replaced out wide by Scully.

He played a part in the lead almost being strengthened soon after the restart, cleverly dummying Whyte’s centre for Bishop to fire inches past the post.

Saydee then won a free-kick that was sent towards the back post by Pack, but a stretching Poole could not make a connection.

It appeared to be only a matter of time before Pompey scored again – and the third goal did arrive in fortuitous fashion on 51 minutes.

Whyte crossed from the right and BECKLES tried to clear, but only succeeded in sending the ball looping into his own net.

Another changed followed just past the hour mark, as Saydee made way for Manchester City loanee Alex Robertson.

Pompey were passing the ball around with ease and one such move ended with Whyte drilling in a shot that Howes tipped around the post.

The winger was given a chance to rest up on 74 minutes, with summer signing Jack Sparkes handed a chance to impress.

He was immediately involved in the action, capitalising on Howes making a mess of Rafferty’s cross by firing the ball across goal, but Bishop could not get on the end of it.

Pompey were cruising towards victory, although a long-range rocket from Idris El Mizouni flashed narrowly over their bar.

The hard-working Bishop and Joe Morrell were handed breathers late on, with Yengi and Sean Raggett afforded cameos.

And it was YENGI who wrapped up an excellent afternoon in the capital, calmly sending Howes the wrong way from the spot after being tugged down in the box by the hapless Beckles.

Leyton Orient (4-2-3-1): Howes; Hunt, Beckles (c), Happe, Sweeney (Turns 69); Brown (Graham 78), El Mizouni; Archibald, Moncur (Sanders 69), Sotiriou; Pigott (Pegrum 69)
Booked: Hunt, Beckles
Subs not used: Byrne, Obiero

Pompey (4-2-3-1): Norris; Rafferty, Poole, Shaughnessy, Ogilvie; Morrell (Raggett 86), Pack (c); Whyte (Sparkes 74), Saydee (Robertson 61), Kamara (Scully 46); Bishop (Yengi 86)
Goals: Pack 23, Bishop 44, Beckles 51 (og), Yengi 90+3 (pen)
Booked: Robertson, Yengi
Subs not used: Schofield, Devlin

Referee: Ollie Yates

Attendance: 8,372 (1,246 Pompey fans)