Celtic saw off Hearts while Aberdeen beat Rangers.
Here, Press Association Sport looks at five things we learned from the action.
Ryan Christie can be a big-game player for Celtic
The former Inverness player came off the bench at half-time and had a hand in all three goals, winning a penalty, seeing a shot spilled for James Forrest to net the rebound, before hitting the goal of the game from long range. The 23-year-old has spent most of his time under Brendan Rodgers on loan at Aberdeen but the Celtic boss described his performance as “sensational”.
Hearts’ squad depth is set for a serious test
Craig Levein’s side lacked a threat after Steven Naismith went off early on with knee trouble. With Christophe Berra, John Souttar and Uche Ikpeazu out long term and Clevid Dikamona and Peter Haring struggling with injuries, Hearts could be down to the bare bones in central defence – especially for big league games against Hibernian and Celtic in the coming week.
Rangers’ wait for major honours continues
Steven Gerrard has undoubtedly revived the team, taking them into the Europa League group stages, but their domestic form away from Ibrox remains patchy. Major silverware has not been seen at Ibrox since 2011, a year before Rangers went into liquidation, and the rebuilding job is still ongoing.
Aberdeen cannot be written off
The Dons travelled to Hampden in eighth place in the league after struggling to replace the goals of Adam Rooney and creativity of Kenny McLean following their summer departures. But Lewis Ferguson’s header upset the odds to make it four cup finals under Derek McInnes.
Umar Sadiq still needs improvement
With Alfredo Morelos suspended and Kyle Lafferty cup-tied, the on-loan Roma player was handed his first start after Gerrard recently declared he had to improve in every department to get more game time. But he failed to seize his chance, missing an early headed opportunity and being continuously caught offside, to his manager’s clear frustration. His day went from bad to worse when he was booked for a dive in the penalty area.