The Gunners appeared to be handed a favourable draw for the openingstages of Europe's elite club competition, with Shakhtar Donetsk andPartizan Belgrade making up the other opposition in Group H.
Making a point: Arsene Wenger wants Arsenal to be vigilant
Wenger's men are again expected to progress to the knockout rounds, where they were beaten by Barcelona in the quarter-finals last season.
However, the Arsenal manager insists taking qualification for granted would be unwise as they prepare for the visit of the Portuguese runners-up, who beat Celtic as they came through two qualification rounds.
'For us a win next Wednesday night is vital, because I believe the group is much more difficult than people expect it to be,' Wenger said.
'Braga finished in front of Porto last year - we played against Porto and know they are a good side. Also, they have just kicked Seville out in the play-offs.
'Shakhtar Donetsk are one of the best European sides, that is why I believe it is very important we start well at home.'
Defender Thomas Vermaelen should be fit from the Achilles problem which ruled him out of today's Barclays Premier League clash with Bolton at Emirates Stadium.
However, neither Robin van Persie nor Theo Walcott will be available for possibly up to six weeks.
Big responsibility: Marouane Chamakh will spearhead Arsenal's attack
Arsenal travel to Belgrade for their first away European match at the end of the month.
Wenger knows beating the Serbians would go a long way to helping secure safe passage to the knockout stage - but only if they can get the required result against Braga first.
'Belgrade is a good opportunity - if you want to well in the Champions League you need nine points from your home games and you need one result away from home,' Wenger said.
'But let's first start well against Braga and then we will see how far we can go.'
With Denmark forward Nicklas Bendtner also recovering from injury, as he continues to be troubled by a groin problem, more responsibility will fall on summer signing Marouane Chamakh.
The Morocco forward scored on his home Barclays Premier League debut in the 6-0 win over Blackpool, and Wenger believes his style is very much suited to the English game.
However, the Gunners boss is also in no doubt the former Bordeaux frontman is also tailor-made for a European campaign.
'Chamakh will adapt well because he is a player who, no matter what game you play, likes to connect with players on the pitch,' the Arsenal manager said.
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