Momentum is a curious thing. It takes a while to warmup and can go cold suddenly but right now it is fuelling Arsenal. This was not their most inspiring performance of recent weeks but they possessed enough grit to extend their winning sequence in all competitions to 11 and stamp control on Group E in the Europa League.

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Danny Welbeck inflicted a rare home defeat for Sporting, who have not lost a game at the Estádio José Alvalade since Barcelona rolled into town just over a year ago.

Unai Emery’s desire to win the group as quickly as possible while keeping his players bubbling is palpable and he described this win as “a big positive thing”. Coming into the game he had talked about his liking for the spectacle, for the panache of the goals that had flavoured recent victories. But this match was more about sticking at it when their game lacked some slickness and that in itself showed a different side of the team he is building.

Another victory edges Arsenal that bit closer to the club’s record of consecutive wins, which stands at 14. Emery took a deep breath as he considered that. “Three matches,” he mused. “They are a lot of matches. We are thinking only of the next one against Crystal Palace and also to enjoy each moment. We want to continue to win but we know we can lose at any moment.”

That dash of realism stems in part from Arsenal’s habit for strangely sluggish first halves. That offered Sporting plenty of encouragement to try to take the initiative. The Lisbon team strained for that touch of precision or finesse to cause major problems but it was obvious they wanted to get the ball forward directly as often as they could.

Facebook Twitter Pinterest Sporting’s Nani is tackled by Arsenal’s Pierre-Emerick Aubameyang. Photograph: Antonio Cotrim/EPA

Just after the half-hour Nani energised the crowd with a sudden change of pace and direction to give himself a shooting chance. His strike fizzed just over the bar. If that lifted the crowd, the mood sharpened moments later when Sokratis grabbed a chunk of Fredy Montero’s shirt as the Colombian stretched his legs. Down he went, and the screeching whistles cascaded down from the stands as the referee waved play on.

All Arsenal had to show offensively from a tepid opening 45 minutes was a free-kick from Henrik Mkhitaryan which Renan Ribeiro beat away. The fluency and urgency was lacking, and the half-time whistle begged the question as to why Arsenal find their gears only in the second half – and if they might find themselves with too much ground to make up one of these days.

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Emery is well aware of the phenomenon even if he has not quite sorted out the problem yet. “Each match is a very big opportunity to improve and one area is this,” he said. “We spoke about it before the match. In the dressing room at half-time we said we cannot impose our game in the first 45 minutes but we have the opportunity to change the result in the second half and think only of winning this match and improving things. We did that. We need to continue finding the solution for the first half to be better.”

There was an upturn just after the restart as Pierre-Emerick Aubameyang was sent scurrying towards goal twice in quick succession. On both occasions the quality of the pass was incisive, although he had to shoot from sharp angles. Both times Ribeiro denied him.

Midway through the second half Welbeck found the net with a powerful header, only for the referee, Damir Skomina, to disallow the goal for a foul. The decision looked debatable.

Their goal came fortuitously, as Sporting were punished after a slip by Sebastián Coates. The defender tried in vain to deal with a backheel from Aubameyang but diverted the ball for Welbeck to power forward and steer past Ribeiro.

Sporting’s manager, José Peseiro, raged about all sorts of perceived injustices but it was hard to see what was wrong with the goal.

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Emery is endeavouring to foster a sense of one squad all in it together, and the majority of players he will use at Selhurst Park on Sunday were in the travelling party to Lisbon, even if Mesut Özil did not play. Alexandre Lacazette and Alex Iwobi had short cameos. It is part of that desire to maintain momentum for as long as possible – and to make it robust enough for the time when this run veers off course.

A year ago, three games into the Europa League group stage, Arsène Wenger took a hotchpotch group to Red Star Belgrade drawn from established players who were not getting any Premier League minutes mixed in with 10 academy boys making up the matchday squad. While Wenger utilised two completely different teams in league and cup competitions, Emery’s way is to promote the feeling of one squad, regardless of the opponents or prize.

Eleven wins and counting, Arsenal’s next hurdle awaits on Sunday lunchtime in south London.