In a week that Celtic skipper Neil Lennon announced he would be leaving Parkhead at the end of the season, it was his young namesake from Ibrox who helped Rangers side to their first success in this competition for five years.
Goals by Andrew Shinnie and Dean Furman completed a night of misery for Celtic, who had a collective nightmare.
The match was delayed for 15 minutes to allow the impressive crowd of 11,486 into the ground, some 3,000 more than watched the Tennent's Scottish Cup semi-final replay between Hibs and Dunfermline on Tuesday.
There had appeared to be little to separate the two teams before kick-off, with both tied at the top of the league table with one game remaining - but the rout began after only four minutes. Rangers striker John Fleck took possession on the left before laying the ball off to Shinnie at the edge of the Celtic box.
The young forward still had a lot to do but he showed impressive ability to fashion a yard of space before sending his low drive into the corner of net past goalkeeper Paul Skinner.
Moments later, Lennon set up Fleck, whose left-footed drive from ten yards clipped the post before the Celtic defence cleared the danger.
In the 20th minute the Ibrox young guns doubled their lead in spectacular fashion when Lennon sent a volley from around 35 yards dipping over Skinner and into the net.
Rangers all but killed off the game when they made it 3-0 ten minutes into the second half, Lennon racing through the overworked Celtic defence all too easily on the counter-attack before rounding the tentative Skinner and slotting the ball into an empty net.
Fleck should have made it four when he robbed Celtic skipper Paul Caddis and drove at goal. This time Skinner came out to block, but the next Rangers goal - and Lennon's hat-trick - had been delayed only momentarily.
In the 62nd minute they were awarded a penalty when Celtic defender Jason Marr brought down Jordan McMillan, allowing Lennon to complete a night to remember by sending Skinner the wrong way.
In the 69th minute, with the Parkhead defence missing once again, Skinner made a good save from Lennon only for Rangers skipper Dean Furman to pounce on the loose ball and slot home his side's fifth goal, prompting an exodus from the Celtic end of the stadium.
Lennon, whose performance was witnessed by Rangers boss Walter Smith, hailed the experience as "the best night of my career" and hopes that he might figure in the Rangers first team before the end of the season.
He added: "If the first team secure second spot in the league then hopefully the manager will give me a second half or something."
Rangers Under-19s manager Billy Kirkwood said: "The boys will remember that for the rest of their lives.
"Coming to the national stadium and getting a result like that is absolutely fantastic. We controlled the game, picked them off and scored some great goals."
His stunned Celtic counterpart John McLaughlan, who kept his players in the dressing room for an hour after the game, said: "I'm just thankful it wasn't more. It was in front of a fantastic Celtic support which was more embarrassing and I would like to apologise to them."
Celtic: Skinner; Caddis, Marr, Anderson (Traub 72), Lafferty (Monti 69); Cawley, Hepburn, Millar (Connell 64), Carey; Cahillane, Sheridan. Subs not used: Barron, Kiely
Rangers: Gallacher; McLachlan, Kinniburgh, Perry, Smith; Emslie (Djeziri 82), Furman, McMillan, Shinnie; Lennon (Little 78), Fleck. Subs not used: Sagar, Harvey, Ness.
BOYD TIPS NAISMITH TO MOVE ON TO 'ANOTHER LEVEL'
RANGERS striker Kris Boyd has tipped former Kilmarnock team-mate Steven Naismith to handle a possible big-money move, writes Angus Wright.
Naismith, named SPFA Young Player of the Year at the weekend, has been linked with moves to Hearts and Rangers, although Kilmarnock have yet to receive any bids. Boyd told STV's Scotland Today: "He has done really well this season, he's on 17 goals.
"For someone to do that at Kilmarnock, at that level, it's a credit to them and he'll be looking to move on another level."
Kilmarnock assistant manager Billy Brown insists there are still no bids on the table for Naismith. Brown said: "Until a bid comes in, it's hard to say that we're resigned to losing him. We just hope there is someone we can bring in if Naisy does go, but he's down on my list for pre-season training in Italy at the moment."
Boyd, meanwhile, has backed Rangers skipper Barry Ferguson's claim that Walter Smith should have won the manager of the year title.
Celtic manager Gordon Strachan won the SPFA award hours after his side clinched the Bank of Scotland Premier League title.
But Boyd feels Smith's record since succeeding Paul Le Guen, coupled with his reign in charge of Scotland, was a better achievement.
Speaking at the launch of Nike's new Total 90 Laser boot, Boyd said: "I have to agree. To leave Scotland where they were [top of their Euro 2008 qualifying group] and be unbeaten in domestic football since January is a fair feat."