The eight group winners and three best runners-up will join Rangers, Celtic, Hibernian, Aberdeen and holders St Johnstone in the next round.
Hearts are confirmed as group winners ahead of Sunday's home game with Inverness CT, live on Premier Sports at 5.15pm. Stirling Albion will finish runners-up if they beat Peterhead at Forthbank.
Dundee United finished with a 100% record. Arbroath and Kelty Hearts meet at Gayfield and are looking to join United in the last 16. East Fife and Elgin City clash at Bayview, with both still to pick up a point.
Dundee lead the way from Forfar Athletic by a single point ahead of their encounter at the Kilmac Stadium. Ross County host Montrose in the other match but both are out of contention.
Raith Rovers will seal top spot if they beat Alloa Athletic at Stark's Park. Livingston and Cowdenbeath - who meet at the Tony Macaroni Arena - will be hoping to take advantage of any slip-up by Raith.
Ayr United are confirmed as group winners after Falkirk were unable to fulfil tomorrow's fixture. Hamilton Accies host Albion Rovers, knowing a win could take them through as runners-up.
Queen's Park are top but have completed their fixtures. Airdrieonians, who go to Queen of the South, and Motherwell, who are at home to Annan Athletic, are just a point behind the Spiders.
Leaders Stranraer face Kilmarnock in a big game at Rugby Park and Clyde, who take on Morton at Cappielow, also still have aspirations of progressing.
St Mirren have won three out of three and host Partick Thistle in their final fixture, live on Premier Sports on Sunday. Dunfermline Athletic could also still qualify and are at home to Stenhousemuir on Saturday.