Former Rangers players Kris Boyd and Gordon Smith say their defeat to Progres Niederkorn in the Europa League is possibly the worst in the club's history and 'extremely embarrassing'.
Rangers crashed out at the first qualifying stage against the part-timers from Luxembourg, who had never won a game at European level before Tuesday night.
Niederkorn had managed just one goal in their previous 13 ties but second-half strikes from Emmanuel Francoise and Sebastien Thill handed them a 2-0 second-leg victory and a 2-1 win on aggregate.
The result could also have serious ramifications for Rangers domestic hopes too, according to Boyd.
The Kilmarnock striker, who had two spells at Ibrox, told Sky Sports News HQ: "This result is up there with the worst in the club's 140-year history, there's no doubt about that.
"To get beaten by a team of part-timers that finished fourth in their league last season and be knocked out before the season has really started is very disappointing. Until the league campaign has started we will not see how damaging this result will be.
"The rest of the Premiership clubs that are not in Europe will be involved in League Cup games for the next four weeks, hard games to get them up to speed for the start of the league while Rangers' next competitive game will now be their opening league game.
"All the teams in around them are going to have a head start on them in terms of their competitive preparation and they cannot afford a slow start in the league."
Former Rangers player and director of football Smith said the "reputation of the club has been damaged" by the defeat, believes it is the worst European result in the club's history and compared it to their Scottish Cup loss to Berwick Rangers in 1967 which shocked Scottish football.
"It's extremely embarrassing and it is also costly as well because Rangers were hoping to have a run, they have brought in some players, spent a bit of money and hoping to have a good run in Europe," he told Sky Sports News HQ.
"Even Pedro Caixinha was talking about being in the group stages, that would be success in itself, and to go out in the first round to a part-time team from a small nation like Luxembourg is very embarrassing.
"It is the worst European result in the club's history, it might even compare as the worst overall because of the level of opposition. A lot of people refer back to Berwick in the cup in 1967 when Rangers lost that game but this really does compare with that, it is pretty poor."
Pedro Caixinha came in for criticism following Rangers' 5-1 defeat to Celtic at Ibrox in April but has been backed by the board to re-shape the squad with eight summer signings confirmed so far.
Boyd added: "Pedro Caixinha has been backed with money and you would be hoping to be in the next round of the Europa but last night it just looked like a team that was set out hoping something was going to happen rather than making it happen. The game was so flat from start to finish.
"When you don't finish teams off in the first leg then you run the risk of what happened last night."
Smith believes the Portuguese will be given time but says improvements must be made quickly.
He said: "Things aren't looking very good at the moment for the manager, he will be given time, I think, because he has brought in players, he has only just taken over but Rangers are in a real transition period and he needs to get things going very quickly."