The Railwaymen arrived in Portugal heavy underdogs, but a resolute defensive display combined with some slick counterattacking play, saw them jet home with a three-point haul
Ex-Braga player Rafael Bastos struck twice in the first half as his new side turned in a mightily impressive performance to down the Portuguese.
Os Arsenalistas were pre-match favourites and justified the tag with an enthusiastic, dominant start to the game. Hugo Viana and Custodio settled into an early groove to help Braga control the opening 10 minutes.
Cluj pressed doggedly early on but were unable to gain a foothold in the game. The chances soon started flowing for Braga, and Custodio in particular won a free-kick and took a pop at goalkeeper Mario Felgueiras in the opening 20 minutes.
Braga's midfield was growing in confidence and as they dominated possession, a goal only seemed likely at one end of the pitch - but Ioan Andone's side had other ideas.
Breaking from a Hugo Viana corner, Modou Sougou sprinted down the left, attracted the attention of the last defender and slotted a perfect through-ball for Bastos to finish when one-on-one with Beto.
Braga remained undeterred, however, and continued to enjoy the better of the attacking play. Space down the flanks became particularly easy to find and Alan kept his team ticking over well in the final third.
After a number of blocked shots from the home team, an equaliser looked inevitable, but again it was the visitors who struck.
After Pantelis Kapetanos missed a gilt-edged chance to make it two, Bastos struck for a second time. The build-up was a little lucky, but the arrowed finished into the top right-hand corner was no mistake.
After the restart, both teams picked up where they left off. Braga controlled the tempo, while Cluj remained happy to put men behind the ball in increasingly large numbers.
With the Railwaymen packing the central area in front of their own penalty box, Os Arcebispos were limited to long distance shots and sideways passes that failed to penetrate the opposition defence.
With a change in philosophy needed after an hour, Jose Peseiro's men altered their style. Felguerias' goal came under siege as shot after shot was fired in, but block after block was made. Ze Luis was introduced at the expense of Hugo Viana, but still the Portuguese side failed to break their opponents down.
With time running out, Peseiro's men saw a number of headed chances miss the target when they ought to have tested the goalkeeper. In the end Andone's Cluj hung on to keep a clean sheet away from home and ramp up the pressure on group rivals Galatasaray.