Celtic swept Rangers away with an emphatic second-half performance to record their first Ibrox success in seven years.
Lubo Moravcik netted a sweetly-converted double before Henrik Larsson notched his 50th goal of the season late on.
It was also Rangers' third successive home defeat and further proof of how much Martin O'Neill's team has dominated football in his first season in Scotland.
Celtic can now look forward to clinching the treble by lifting the Scottish Cup safe in the knowledge that every other task, apart from one amazing, irrelevant blip at Ibrox earlier in the season, had been achieved.
The early pressure came from the home side with Jorg Albertz eager to let fly from distance. Barry Ferguson almost produced an even more impressive strike in the 21st minute. Rod Wallace also narrowly missed the target with a header.
Celtic had struggled to create much from open play but had caused problems instead from set-pieces, with Johan Mjallby getting free at the far post. The Swede could not hit the target and Celtic went in at half-time looking no more dangerous.
Moravcik's first half had been a quiet one, with Ferguson running the show in midfield. But it was the veteran Slovak who opened the scoring.
From a free-kick by Neil Lennon, Larrson held the ball up and then slipped it into Moravcik's path, with Ferguson having failed to track his run into the box. The finish was an assured one.
That prompted two substitutions, with Rangers taking Bert Konterman off and sending on Tugay. Celtic replaced Tommy Johnson with Sean Maloney and he almost scored within two minutes of coming on.
Lennon's tackle on Amoruso set up a counter-attack that saw three Celtic men with just a single defender facing them and Larsson set up the youngster. His finish was straight at Stefan Klos - but not long after he was celebrating a goal assist.
Douglas hoofed the ball downfield, Maloney headed on and Moravcik sent the away fans ecstatic by turning Ricksen in the box and stroking the second past Klos.
Ricksen was booked for using a leading elbow on Alan Thompson, becoming the third Ranger to be yellow-carded alongside Ferguson and Craig Moore.
Moravcik was withdrawn to huge applause by the away following and his replacement, Jackie McNamara, set up Larsson for the killer third strike.
The Swede rounded Klos and despite a taxing angle managed to squeeze the ball into the net for his 50th goal of an amazing season. Larsson almost made it four but with Moore closing him down he could only fire at Klos.
RANGERS: Klos, Moore, Konterman (Tugay 65), Amoruso (Wilson 72), Ricksen, Ferguson, Albertz, Numan, Wallace, Flo, Dodds (Fernandes 73). Subs Not Used: Christiansen, Leven. Booked: Ferguson, Moore, Ricksen.
CELTIC: Douglas, Mjallby, Vega, Valgaeren, Agathe, Lennon, Lambert (Boyd 89), Moravcik (McNamara 86), Thompson, Johnson (Maloney 67), Larsson. Subs Not Used: Gould, Healy. Booked: Lennon. Goals: Moravcik 61, 74, Larsson 87. Attendance: 50,057.
Referee: S Dougal (Scotland).
