Following Hearts’ 4-2 win over St Mirren at Tynecastle on Saturday evening, they were joined by their Edinburgh rivals Hibs and cinch Premiership champions Rangers.
Hibs booked their spot in the last four with a 2-1 triumph over Motherwell, with Norwegian teenager Elias Melkersen scoring a brace on his first start for the club. Motherwell did score via Joe Efford but were up against it from the first minute after Bevis Mugabi was sent off after 49 seconds.
Rangers had it altogether more comfortable, winning 3-0 at Dundee via goals from Connor Goldson, James Tavernier and Fashion Sakala.
One tie remains, with Dundee United welcoming Celtic to Tannadice on Monday, with a 7.45pm kick-off.
When is the draw?
And at the conclusion of that match, the draw will be made live on Premier Sports, who are broadcasting the match live from Tayside.
The draw will also be on BBC Radio Scotland.