Ross County and St Mirren are the only non-SPL sides left in the competition, and they both have a tough task with away ties at Aberdeen and Celtic respectively.
The four ties are scheduled as follows:
Friday, 17 February, 2006
Inverness Caledonian Thistle v Livingston (Tulloch Caledonian Stadium, 1.30 pm)
Sunday, 19 February, 2006
Aberdeen v Ross County (Pittodrie Stadium, 2 pm)
Rangers v Heart of Midlothian (Murray Park, Milngavie, 1 pm)
Friday, 24 February, 2006
Celtic v St Mirren (Excelsior Stadium, Airdrie, 7 pm)