Lyon’s 4-2 home win over Stuttgart means Gers are now at least assured of parachuting into the Uefa Cup in February as the third-placed team in Group E.
But the French side’s success also means Barca are not yet guaranteed of a place in the last 16 of the more lucrative tournament.
They will still need to win when they travel to the Stade de Gerland later this month to be sure of progression.
That can only bode well for the Light Blues, who will play Stuttgart – a team now without any competitive interest in the competition – at the same time in Germany.
Winning that game and Barcelona edging past Lyon would put Walter Smith’s team through before the French travel to Glasgow next month.
With their victory against Rangers, the Spaniards secured their first home win against a Scottish side after two defeats to Dundee United and a pair of draws with Celtic.
Thanks to the clean sheet they kept, their status as one of just two teams in this season’s Champions League still to concede – Arsenal being the other – also remains.
Ibrox manager Smith made two changes to the Gers side which beat Inverness 2-0 on Saturday as he reverted to the 4-5-1 system which worked so well in Lyon.
Kris Boyd and Nacho Novo dropped to the bench, with Charlie Adam coming in as the fifth man in midfield and Daniel Cousin ploughing a lone furrow up front.
Barca were excellent when they beat Real Betis 3-0 on Sunday and were eager to pick up from where they left off.
It took them just six minutes to break the deadlock through Thierry Henry – but the goal should never have stood as he steered the ball home with his arm.
Ronaldinho played a part in the opener, crossing deep from the left to Lionel Messi as he charged in from the right.
His header came off Allan McGregor’s right-hand post and as Henry slid the rebound in, the ball hit his arm but Dutch linesman Hans Ten Hoove failed to spot the foul.
The hosts pushed for another and came close through Messi’s curler from 20 yards but Rangers slowly began to settle.
Brahim Hemdani and Lee McCulloch combined to set up DaMarcus Beasley, whose tame header ran just wide.
And although the Spanish outfit hit back with Andres Iniesta and Ronaldinho’s chances – the latter saved superbly by McGregor – Gers started getting more possession.
What they lacked was clear-cut chances and Barcelona made them pay for that with their second goal three minutes before the interval.
Ronaldinho was the architect, combining with Messi to play a neat one-two between Allan Hutton and Carlos Cuellar and put himself in on goal.
Although McGregor got down well to block the Brazilian’s low shot, the ball then fell to his Argentine colleague and he rolled into the net from four yards.
Messi should have struck again after the break but McGregor got down well to keep his placed effort out with his legs.
Carles Puyol and Henry also forced saves from the Scotland squad member as Frank Rijkaard’s men turned the screw.
For all their opportunities – Xavi and Messsi could have netted further counters – the Catalans could not add any more gloss to their win.
Indeed it was Rangers who came closest in the closing stages, a rasping Jean-Claude Darcheville free kick being held well by Victor Valdes before the keeper stopped Novo’s volley.
Failure to strike back means Gers’ European focus now turns to Stuttgart on November 27 and the match which may still take them beyond their section.
BARCELONA: Valdes; Puyol (Oleguer 84), Thuram, Marquez, Abidal; Xavi, Yaya Toure, Iniesta (Gudjohnsen 70); Messi, Henry, Ronaldinho (Bojan Krkic 76).
Subs not used: Jorquera, Sylvinho, Giovani.
RANGERS: McGregor; Hutton, Cuellar, Weir, Papac; Beasley (Novo 68), Hemdani, Ferguson, Adam (Darcheville 61), McCulloch; Cousin (Naismith 77).
Subs not used: Carroll, Boyd, Whittaker, Faye.