The four best group winners will join Celtic, Rangers, Motherwell and Aberdeen as the seeded teams in Sunday's draw.
The eight group winners all qualify along with the four runners-up with the best records.
Here PA takes a look at how the land lies in each of the sections:
Hearts have already qualified as one of the seeded teams after completing their fixtures with 12 points. Raith Rovers can move on to eight points if they win at Cowdenbeath but they will need to rack up the goals to stand any chance of progress - they have a negative goal difference and will need a five-goal victory to beat Dundee United's record, for instance, which would probably still not be enough.
Dundee and Hibernian are both on nine points ahead of Sunday's meeting at Easter Road. Whoever comes out on top will qualify but the other team stand a good chance of joining them, especially if the game ends in a draw.
Peterhead and St Johnstone's clash at Balmoor will decide who wins the group. Only a Saints victory would allow Dundee United to clinch second spot but their eight-point tally, with a goal difference of four, is unlikely to carry them through.
Ross County will win the group if they beat Stirling at home as expected but would need other results to go their way to finish as one of the four best winners. Arbroath and Elgin meet at Gayfield and victory for either team would stand them in good stead.
Unbeaten Dunfermline only need a point when they host Clyde at East End Park to overtake current leaders Falkirk. But the Pars could still make it through as one of the best-placed runners up even with a surprise defeat to Danny Lennon's League One outfit.
Annan lead the way on seven points having played all four games but their goal difference means they are guaranteed to finish second behind whoever takes the most points from Ayr's clash with Stranraer at Somerset Park. Sadly for the Galabankies, they are unlikely to have enough to make the second round.
Victory for St Mirren at Hampden will guarantee the Buddies top spot but the winner of the clash between Partick Thistle and Morton could pinch automatic qualification if Saints only take a draw and miss out on the bonus point. A victory at Firhill is almost certainly a minimum requirement if either the Jags or Ton are to stand a chance of claiming a best runners-up slot.
Alloa will be hoping for a Livingston slip-up when Gary Holt's team host Airdrie. The Wasps must beat Stenhousemuir, hope for Lions to lose and pray for a swing of eight in the goal difference stakes for them to have any hope of topping the group. Beating the Warriors would give Peter Grant's team an outside chance of making it through in second.