Gavin Rae, Nacho Novo and Sasa Papac came in for their first starts of the season, while Kris Boyd, Charlie Adam, Libor Sionko, Brahim Hemdani and Alan Hutton all came back into the starting line-up.
The manager was rightly angry and dissatisfied following the game at Easter Road and threw the gauntlet down to his stars ahead of this match, insisting they make amends by progressing into the next round of the CIS Cup.
Having produced possibly their worst display of the season here at East End Park just last month and with the threat of extra time looming, should the 90 minutes end goalless, the Light Blues knew there was no room for error.
But with nothing of any real note to speak of in the opening 10 minutes it looked like it was going to be another one of those nights.
With 12 minutes gone Papac left Jim Hamilton in a crumpled heap on the edge of the area and the free kick was given.
Allan McGregor, facing the side he spent last season on loan with, lined up his wall accordingly and it was effective as Adam blocked Hamilton’s thundering shot.
Three minutes later Novo was felled by Gary Mason at the other end, but Dunfermline defended Adam’s curling left-foot cross well to clear the danger.
With Sionko patrolling the right flank, Chris Burke started the game on the left and after 19 minutes almost set up the opener for Kris Boyd.
He whipped in an inviting cross and the on-form striker managed to get his header on goal, but it bounced and came back off the cross bar. It was a decent chance and one Boyd could have stuck away.
Two minutes later, however, Hamilton passed up an even better chance to put the home side in front.
Steven Simmons curled in a corner from the right and the former Motherwell striker broke free at the back post to power a header just wide.
On 42 minutes Novo split the Pars defence when he sent Boyd on his way, but the Scotland international’s first touch let him down and Dorus De Vries smothered.
A minute before the break Adam tried his luck from long range but his effort flew over the bar.
There was real sense of urgency in Rangers’ play after the break as Le Guen’s men came bursting out of the blocks.
Novo collected just inside his own half and following a combination of trickery and good fortune, burst past three Dunfermline defenders to play in Sionko, who had switched to the left.
The Czech international curled in a fine low cross into the box, but the Pars finally cleared before Novo nipped in for a sure goal.
After 51 minutes Burke set off on a mazy run down the right and crossed for Boyd but he was always stretching and his header looped over the bar.
Within 60 seconds Burkey was on his way again but instead of feeding Sionko who was unmarked at the back post, he opted to shoot and his drive rolled wide.
Looking much more lively, the Light Blues continued to press and Souleymane Bamba did brilliantly to intercept Sionko’s dipping cross, ahead of Boyd who was primed for a shot.
On the hour mark, Dunfermline were carved open again down the right and this time it was Hutton who provided the cross. His low drive into the area found Boyd, who tried a back-flick on goal but McGuire blocked twice before the danger was cleared.
A minute later the former Kilmarnock striker found space in the box again and should have scored when he bulleted a header past the post from six yards.
With the pressure building on the Dunfermline, it was only a matter of time before the goal came for Rangers, albeit from an unlikely source.
Pars defender Bamba stuck out a leg to clear Hutton’s low cross but the ball skipped up and looped over his own keeper to put the visitors ahead.
Eager to extend the lead Le Guen replaced Novo with Thomas Buffel and within 30 seconds of his introduction he crossed for Boyd, who was inches away from adding a second when he nodded just past the upright.
He didn’t have to wait much longer for his first cup goal of the season, however, and after 72 minutes hit a wonder strike from 25-yards out.
It will certainly be a contender for goal of the season after he collected Allan McGregor’s long ball forward, before spinning and unleashing a wicked shot from long range. It dipped just below the cross bar to give De Vries no chance and put Gers 2-0 ahead.
Adam nearly added a third with another looping long range effort but the keeper was alert and managed to tip the ball over the bar.
DUNFERMLINE: 3-4-3: 29 De Vries, 3 Wilson, 14 McGuire, 24 Bamba, 2 Shields, 8 Mason, 4 Young, 19 Labonte, 7 Simmons (11 Muirhead 63), 17 Daquin (15 Morrison 62), 20 Hamilton
SUBS: 1 McKenzie, 18 Tod, 23 Ross
BOOKINGS: None
RANGERS: 4-4-2: 22 McGregor, 20 Hutton, 7 Hemdani, 5 Papac, 26 Smith, 14 Sionko (32 Martin 58), 11 Rae, 25 Adam, 17 Burke ((23 Sebo 77), 15 Boyd, 10 Novo (4 Buffel 70)
SUBS: 34 Robinson, 19 Svensson,
BOOKINGS: Papac 39
REFEREE: Mike McCurry
Man-of-the-match: Brahim Hemdani