Here's a look at how things stand going into matchday five...
Alloa Athletic are top and a draw at home to Ross County will be enough to progress but the Staggies will claim top spot if they win at the Indodrill Stadium. Arbroath are in second place but have completed their fixtures while winless pair Elgin City and Dundee United meet at Borough Briggs.
St Johnstone need a draw at Forfar to seal first place but will be overhauled by the Loons if they lose at Station Park. Montrose are second but have completed their games and are out of contention, as are Falkirk and East Fife, who meet at Bayview.
Inverness CT have a 100% record and a draw at Tynecastle on Sunday – live on BT Sport – will be enough to win the group. Hearts will leapfrog ICT if they get all three points. Cove Rangers and Raith Rovers have only pride to play for at Balmoral Stadium.
Dunfermline Athletic need a point at home to Stirling Albion to be sure of finishing top but are likely to go through even if they lose. A win for Dundee at home to Brechin City should be enough to at least secure one of the four best runners-up spots.
Leaders Ayr United and Partick Thistle are tied on nine points and a draw at Firhill would send both teams through. Morton and Albion Rovers meet in the other game at Cappielow.
Livingston are on course to qualify and a win over Berwick Rangers at Linlithgow - the game has been moved due to pitch works at the Tony Macaroni Arena - will make sure. Second-placed Airdrieonians need to win away to Hamilton to have a chance of reaching the last 16.
Motherwell will win the section if they beat Clyde at Broadwood - live on BT Sport - but Queen of the South look set to make the last 16 as one of the best runners-up if they are pipped for top spot. Edinburgh City and Stranraer meet in the other game at Ainslie Park.
It's tight at the top but Kilmarnock can't be caught if they beat Queen's Park at Rugby Park. St Mirren and Dumbarton - who go head to head in Paisley - both still harbour hopes of qualification.