Champions Rangers closed to within two games of an unbeaten Scottish Premiership season with a 4-1 win over 10-man Celtic in a thrilling Old Firm derby at Ibrox.
Not since 1898-99 have the Gers gone a full top-flight season without defeat – then winning all 18 matches – but Celtic, themselves 'invincible' in 2016-17, failed to halt their latest bid.
Kemar Roofe chested in a smart opener after 26 minutes and Callum McGregor was sent off for a foul in the build-up to that goal, putting Steven Gerrard's side in complete control.
Although Celtic quickly responded with Odsonne Edouard's close-range header, Alfredo Morelos blasted Rangers back into the lead and Roofe and substitute Jermain Defoe added to their advantage.
A sublime Allan McGregor stop from Mohamed Elyounoussi, who netted in the sides' previous meeting, set in motion a frantic game-turning stretch after a quiet start.
Callum McGregor had been booked just prior to that Elyounoussi effort and then foolishly lunged in on Glen Kamara, although referee Nick Walsh allowed play to continue and Roofe redirected Ryan Kent's wayward shot in before a second yellow card was shown.
Allan McGregor was soon in action again to touch Jonjoe Kenny's cross away, though, and Kristoffer Ajer was up highest from the subsequent corner to nod across goal for Edouard to beat Steven Davis on the line.
But back Rangers came and Scott Bain saved from both Roofe and Joe Aribo yet could not deny Morelos, who broke his Old Firm duck in March and deceived Scott Brown to shoot into the roof of the net.
David Turnbull mistimed a header early in the second half, but Roofe made no mistake from Borna Barisic's measured centre to put the result beyond doubt.
There would be no Roofe hat-trick as he made way for Defoe, yet the substitute got among the goals with a cool finish in the 92nd minute.
What does it mean? Bragging rights belong to Gers
Even if Gerrard's men slip up in the final weeks of the season, they will end the campaign without having lost to Celtic in the league for the first time since 1999-2000.
Celtic, who also lost to Rangers in the Scottish Cup, had four flawless Old Firm seasons in the intervening period (2001-02, 2003-04, 2016-17, 2017-18).
Morelos making Old Firm his own
When Morelos preserved Rangers' unbeaten record with the equaliser in a 1-1 draw at Celtic Park earlier this year, he netted his first Premiership goal in the Old Firm in 14 matches. Now he has his second.
There was an early effort on Sunday from a James Tavernier cross that was so poor it did not even register as a shot, but Morelos made the most of his next opportunity.
The forward – twice sent off in the league in this fixture – has too often come off second-best against Brown but nutmegged the midfielder before finishing.
More Gers misery for McGregor
An awkward Callum McGregor own goal – the first of his Premiership career – gave Rangers victory in January, and his latest clumsy contribution was similarly costly.
The midfielder's challenge on Kamara was rash enough without taking into account his yellow for a foul on Kent two minutes previously, earning his second career red card in the competition.
Rangers must negotiate matches with Livingston, on May 12, and Aberdeen in order to finish the season undefeated. Celtic play next against St Johnstone on the same night as the champions' trip to the Tony Macaroni Arena.