Carlisle United 0 Leyton Orient 1: Below-par Carlisle fell to defeat at Brunton Park as Ruel Sotiriou pounced for Leyton Orient.
The visiting frontman beat the onrushing Tomas Holy to the ball in the 21st minute before slotting into an empty net.
Carlisle, in front of an 8,355 home crowd, could not offer enough in response even though sub Terry Ablade hit the post amid some late pressure.
It stretched their winless home run against the Os to eight games, and saw Paul Simpson's side drop back to 20th in League One.
United were not creative enough overall, offering little in the first half and, despite some improvement after the break, failing to do enough to mount a convincing comeback.
It meant a sixth defeat of the league season as last season's League Two champions moved up to tenth.
Blues boss Simpson named an unchanged XI from United's last league game - the 3-1 win at Bolton Wanderers.
It saw the ten players left out of the side for Tuesday's EFL Trophy defeat to Nottingham Forest Under-21s all recalled.
Ben Barclay was named on the bench on his return to fitness, the defender taking Jayden Harris's place in the league matchday squad.
Orient, meanwhile, made one change, with former Manchester United midfielder Ethan Galbraith coming into the side for Max Sanders.
And it was the visitors who had the better of a tight opening spell, forcing the first chance from an eighth-minute corner which was met by Dan Happe, forcing Holy to tip over the bar.
Another corner soon after saw Idris El Mizouni pick up a clearance outside the box before cracking a shot against the crossbar - Holy able to save Sotiriou's diving header as the Os man attacked the rebound.
Carlisle offered little as an attacking threat with Wellens' side the more dangerous - and on 21 minutes the Londoners caught the Blues cold for the opener.
Sotirou got beyond Sam Lavelle as a ball was threaded through the left channel by Joe Pigott and as Holy came out to try and intercept, Orient frontman Sotiriou skipped past him and stroked the ball into the unguarded net.
Carlisle continued to offer little inspiration in response, with Orient's James Brown dropping a shot wide as the visitors looked for a second, Sotiriou again going close after Owen Moxon's pass was intercepted.
United briefly came to life on 39 minutes when a powerful Jon Mellish run saw the defender fouled 25 yards out, but Moxon's free-kick - the hosts' first shot of the game - struck the wall with the midfielder sending the follow-up sailing into the Warwick Road End.
Soon after, a loud bang was heard from the Warwick but play continued as police and stewards moved into the home end.
The game continued and, moments later, it was almost two for Orient as Sotiriou was played in, but Holy saved at the striker's feet.
For Carlisle, Fin Back was closed down by two defenders as a Jordan Gibson cross broke his way, while at the other end Rob Hunt set up Pigott but the big striker couldn't direct his header.
United reached half-time a goal down and with plenty of work to do in order to inject some creativity into their game.
The Blues began the second half with a bright attack which ended with Joe Garner heading Back's cross over the bar, before a Gibson delivery forced keeper Sol Brynn to tip over the Orient bar.
El Mizouni failed to hit the target from a long Brandon Cooper throw, before a Moxon free-kick was headed goalwards by Garner, Brynn equal to it with a save.
Another El Mizouni chance went begging for the Os, as the visiting captain failed to volley a Pigott cross on target at the back post.
Simpson sent on Luke Plange and Ablade for the last 20 minutes, Sean Maguire and Gibson the players sacrificed, but Carlisle were again struggling to create, though Galbraith's weak Orient finish from a good position kept the Blues in it.
United applied pressure in the closing stages with a series of corners, one of which saw another sub, Ryan Edmondson, have a near-post attempt blocked.
Lavelle narrowly failed to pounce on a Garner header from another while, moments later, Ablade raced onto a Moxon pass and smashed a shot against the outside of the right-hand post;
It was as close as the Cumbrians came as a well-drilled Orient, backed by 424 travelling fans, held on for the points.
United: Holy, Back (Edmondson 81), Armer, Lavelle, Mellish, Guy, Moxon, McCalmont, Gibson (Ablade 70), Maguire (Plange 70), Garner. Not used: Andresson, Whelan, Robinson, Barclay.
Leyton Orient: Brynn, Hunt (Graham 80), Cooper, Happe, Turns (James 75), Brown, Galbraith, El Mizouni, Archibald, Sotiriou (Drinan 57), Pigott (Forde 80). Not used: Howes, Sweeney, Moncur.
Goal: Sotiriou 21.
Booked: Brown, Turns, El Mizouni.
Ref: Edward Duckworth.
Crowd: 8,355 (424 Leyton Orient fans).
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here