Rangers got back to winning ways with a 5-0 win over Dunfermline after three consecutive defeats before Celtic made it four wins on the trot by beating Hearts 3-2.
Raith Rovers pulled off the result of the round by beating Aberdeen 2-1 at Stark's Park.
Here, the PA news agency looks at five things we learned from the weekend's action.
Kyogo Furuhashi is adaptable
After netting four times in three starts as a centre-forward, the Celtic newcomer was shunted out wide amid injuries to accommodate Odsonne Edouard following injuries to Ryan Christie and Liel Abada. The Japan international still got his goal and had a hand in both others, linking up well with Edouard to set up Stephen Welsh. He also had to adapt to some close attention from the Hearts defenders, going down off the ball on four or five occasions in the first half, with Craig Halkett booked when the assistant referee spotted something untoward the final time. Although it was difficult to tell whether there was much in the incidents, Hearts were possibly wary of his pace and trying to halt his runs in behind at an early stage. The 26-year-old responded defiantly, whipping up the crowd to join him in reacting strongly after Halkett's indiscretion, as if to show he could deal with the physicality.
Livingston have lift-off
David Martindale's side are the only team without a cinch Premiership point after two matches and they had scraped through to the second round as one of the best runners-up. But they got a much-needed boost after an injury and Covid-hit campaign so far by knocking St Mirren out on penalties.
St Johnstone have not lost their cup expertise
Callum Davidson suffered his first knockout setback in midweek when Saints suffered Europa League defeat against Galatasaray. But he remains unbeaten in 14 domestic cup ties as a manager after the Perth men beat Arbroath on penalties following a 2-2 Gayfield draw. They had shoot-out success on their way to both cup triumphs last season so do not rule out a hat-trick.
Aberdeen hit a bump in the road
The Dons had risen to every challenge so far, save perhaps for an away trip to Sweden - when the European tie against BK Hacken had been effectively won in the first leg and when they missed a host of chances in an inconsequential 2-0 defeat. Having won every other game, they looked like they were cruising to victory in Kirkcaldy only to suffer a second-half collapse. Ethon Varian's equaliser three minutes into the second half totally transformed the game and Aberdeen's response was too little, too late. Stephen Glass has shown an ability to change games with substitutions but there was no answer this time despite having some of his best players on the bench.
Glasgow and Dundee are the places to be
The quarter-finals will exclusively take place in two cities with Celtic to host Raith and Livingston to visit Ibrox. Dundee will take on St Johnstone, while their next-door neighbours will welcome Hibernian to Tannadice.