Wenger tells Arsenal to quit the damaging habit of complacency

Playing a return game against opposition beaten 6-0 two months earlier ought to inspire confidence in any team. The danger for Arsenal in tonight's Champions League tie here is a drift into the complacency that has infested recent performances away to Shakhtar Donetsk and at home to the old enemy Tottenham on Saturday.

Having beaten the Ukrainians 5-1 at the Emirates, then taken an early lead in Donetsk, Arsenal lost what their manager Arsène Wenger called "focus" and "concentration" in suffering a 2-1 defeat, their former striker Eduardo da Silva almost inevitably scoring the winning goal. Those three points enabled Shakhtar to draw level with Wenger's team at the top of their group on nine points, three ahead of Braga.

Arsenal returned to London for a home defeat by Newcastle, which Wenger insisted was a statistical freak, but he was on less certain ground in claiming the same for the rare embarrassment by Spurs, who came from two goals down to win 3-2. The third home defeat of the season cost his team the chance to travel to Portugal as Premier League leaders.

The manager's explanation on Saturday combined "loss of concentration, basic errors and bad luck". While never prepared to single out individuals, he must have winced at the efforts of his centre-backs Laurent Koscielny and Sébastien Squillaci, who were reunited on Saturday when the former returned after injury to replace Johan Djourou.

Having also blamed lingering fatigue from the midweek internationals for Saturday's falling away, Wenger will change things around this evening, with Kieran Gibbs, Jack Wilshere, Theo Walcott and Nicklas Bendtner as well as Djourou all hoping for a recall. Robin van Persie, who has not started since August, would also have been in contention but has stayed behind to train in London, as have Gaël Clichy and Andrei Arshavin. The captain, Cesc Fabregas, will require a check this morning on his troublesome hamstring.

Wenger accepts that complacency has been a problem and that there is also concern about throwing games away from winning positions. "There's that danger. Mentally it can become an issue," he said before yesterday's flight from Luton to Vigo; the squad are having to travel in and out of Portugal via Spain because of a general strike.

"We are so at ease in some games that subconsciously maybe we feel we just need to go through the motions." On the other hand, he suggested that the Tottenham embarrassment will concentrate minds: "With what happened on Saturday, I think everybody will be focused for a game that we want to win to qualify."

Having reached the second phase of the competition for the past 10 seasons – missing out only in the two years they played home matches at Wembley – Arsenal should still go through, though Wenger would have preferred to qualify as early as possible. He is also keen this year to win the group, as it appears to be one of those seasons in which finishing second will mean a potentially much more difficult game in the knockout round. At the Emirates, Braga briefly looked a good side, who if anything were too adventurous in their 4-4-2 formation, leaving huge gaps that Arsenal exploited ruthlessly with six goals and a superb exhibition of their passing game, in which Fabregas and Wilshere excelled.

The visitors should feel at home in one sense, facing opponents and supporters in familiar red shirts with white sleeves, known as the Arsenalistas after copying Arsenal's strip following a visit to London by their coach in the 1920s.

Braga reached their highest ever position as runners-up to Benfica in the Portugese league last season and then defeated Celtic and Seville in qualification rounds to reach the Champions League for the first time. In the league this season they have been less successful and now lie 10th of 16 teams, despite having won four of their five home games.

Two victories over the weakest team in Group H, Partizan Belgrade, have kept them in contention, and they are guaranteed at least third place and a berth in the Uefa Cup, though they must win tonight to maintain any serious interest in the senior competition. At the weekend they were spared what would probably have been another defeat, away to Benfica, when the cup fixture was postponed because of the Nato summit in Lisbon. David Cameron returned home pleased with the result there, and Arsenal, if they can avoid any further lapses of concentration, should be able to do the same.