The Light Blues turned in an excellent performance in a terrific match in which they led 3-1 at one stage – and now the two sides will do battle again in Glasgow on October 23.
In the autumnal Swiss sunshine, Rangers began the match by far the brighter of the two, with Kai Kennedy twice going close, firstly with a saved free-kick and then with an effort from distance which slipped just wide.
Nathan Young-Coombes was then somehow denied a shot on the end of a Ciaran Dickson cross by a quite remarkable block from the home side, before, with 12 minutes played, Gers grabbed a deserved lead.
Again, it was Dickson with the cross, this time to Dapo Mebude at the back-post. He headed the ball back into the middle, and coming in there to meet it on the slide was Nathan Patterson.
It was well-merited on the balance of play, but the visitors had their goalkeeper to thank for preserving their lead twice within a few minutes of the restart.
Lewis Budinauckas firstly did well to turn a Lewin Blum effort from distance away, before he did superbly as Nico Maier bore down on him but Budinauckas did so well to stand up and eventually block his effort.
More wonderful play from the Light Blues from Dickson and Kennedy ended with Dickson forcing Lars Eicher into a fine stop at his near post, while Budinauckas again kept the lead intact, turning over another Maier effort.
The superb goalkeeper was beaten, however, four minutes into the second half. From fully 25-yards Samuel Kasongo let-rip with a superb effort which curled into the top corner and was well beyond the reach of Budinauckas.
This was now a major test for Gers – but it’s one they took on wonderfully as they struck twice in four minutes to establish a comfortable lead.
Firstly, Kai Kennedy’s corner dropped in the six-yard box for Danny Finlayson to steer home to re-establish the Light Blues’ lead.
Then, after picking the ball up in midfield, Ciaran Dickson drove into space and found the bottom corner with a lethal strike from 25-yards to beat Eicher.
It was superb stuff from the young Gers, and, with their two-goal lead, they took full control of the game, showing experience well beyond their years.
That period lasted until the 75th minute, however, as Mischa Eberhard got clear down the left to enter the area and finish beyond Budinauckas at his far post for 3-2.
Gers looked like they were going to hold out for a superb win to take back to Glasgow, but in injury time, the ball broke in the area for Gabriele De Donno to finish from close-range.
The young Light Blues do, however, have the edge on away goals going into the second leg.
BSC YOUNG BOYS: Eicher, Blum, Bischel, Geiger, Crnovrsanin, Maula, Ris, Kabeya, Ballet, Maier, Kasongo.
SUBS: Zbinden, Amenda, Jenni, G De Donno, J De Donno, Eberhard, Pereira.
RANGERS: Budinauckas, Patterson, Maxwell, Mayo (Williamson, 11), Finlayson, Breen, Mebude, Young-Coombes, Miller, Kenendy, Dickson.
SUBS NOT USED: Hogarth, Butterworth, McClelland, McKee, Lyall, Ritchie-Hosler.
REFEREE: Emmanouil Skoulas