The eight seeded clubs in the last 16 will be European entrants Celtic, Aberdeen, Rangers and St Johnstone, plus the four group winners with the best records.
If clubs are level on points at the end of the group stage the criteria for separating them is 1) goal difference, 2) goals scored, 3) away goals scored, 4) matches won, 5) away matches won, 6) drawing of lots.
Falkirk, Livingston and Motherwell have already sealed top spot in their groups, with the remaining places to be decided this weekend. Dundee and United are likely to be in the draw whatever the result is in the derby.
Second-round ties are due to be played on the midweek of August 8/9.
