Danny Welbeck’s late winner gave Arsenal victory over Sporting Lisbon in Portugal, as they retained their place at the top of Europa League Group E.
The striker pounced on a Sebastian Coates error and slotted a shot through the keeper’s legs after 77 minutes.
Earlier in the second half, Welbeck had a headed goal ruled out after he was judged to have fouled the defender in the build-up.
Arsenal have now extended their winning run to 11 games in all competitions.
After Monday evening’s impressive Premier League win over Leicester, there was plenty of Arsenal optimism, even though they had never beaten a Portuguese side away from home, losing on their past three visits.
The first half seemed to point towards a dreary goalless draw despite the Gunners controlling the possession – with the visitors managing just two tame shots on target before the break.
Nani had Sporting’s best chance with a high curling effort after half-an-hour before Arsenal winger Henrikh Mkhitaryan’s free-kick was punched away by keeper Renan Ribeiro.
But Arsenal picked up their performance slightly in the second half as Pierre-Emerick Aubameyang was denied twice.
His chip was well saved after he had used his pace to get in behind centre-back Coates and he had a shot saved from a wide angle.
Those chances seemed to spark a bit of life into Arsenal and shortly afterwards Matteo Guendouzi’s cutback found Welbeck, only for his close-range shot to be deflected out for a corner.
But Arsenal’s determination to turn their 67% possession into a goal eventually paid off.
Welbeck’s form under Emery continues to improve and he has now bagged five goals in 10 appearances this season – including two in the Europa League.
Arsenal remain top of the group with nine points from three wins, while Sporting trail in second.
On the whole, the hosts showed little attacking intent – Sporting choosing to defend deep and counter-attack in rare spells.
Full-back Marcos Acuna caused a few problems in the first half for stand-in right-back Stephan Lichtsteiner down the flank, as well as winning a number of corners with some energetic runs through the middle.
There were a few neat touches from former Manchester United winger Nani too but Arsenal never looked like conceding despite manager Unai Emery making six changes to his starting XI.
Lucas Torreira did see a set-piece palmed away before Welbeck’s goal condemned the home side to defeat – but they are still in position to make the knockout stage.
Arsenal’s heavy fixtures schedule – which includes three games in seven days – meant Emery was forced to make changes and he will have been delighted it paid off with a win.
However, there were a few nervous moments in the first half as stand-in full-backs Granit Xhaka and Lichtsteiner were thrown in the deep end because of injuries to Nacho Monreal and Sead Kolasinac.
Midfielder Xhaka was beaten by one Nani run in the first half but was backed up by Rob Holding and he conceded a few fouls for mistimed tackles when out of position.
All-in-all though, Xhaka was fairly solid in comparison to Lichtsteiner, who seemed to struggle in one-on-one situations.
He looked out of his depth and was beaten early on by Sporting full-back Acuna and was lucky not to give away a penalty when he held back Nani in the area before the break.
But he was better going forward and a nice run in behind was picked out by Guendouzi in the first half and after 20 minutes, he was the only Arsenal player to have a touch in the opposition box.