Adama Sidibeh and Benji Kimpioka both scored twice
St Johnstone recovered emphatically after what Craig Levein described as their "terrible" midweek performance with a five-goal thrashing of East Fife to progress to the last 16 of the Premier Sports Cup.
The manager did not mince his words in the aftermath of their defeat by Alloa Athletic, but there was no need to repeat them as his side ran rampant at McDiarmid Park.
Adama Sidibeh scored either side of Benji Kimpioka in the first half to send Saints on their way to the top spot - with the knowledge Greenock Morton were beating Alloa.
Alan Trouten pulled one back for Dick Campbell's visitors, but Mackenzie Kirk scored his first for the club since joining from Heart of Midlothian to restore the three-goal lead before Kimpioka grabbed his fifth of the group stage in stoppage time.
St Johnstone will learn their last 16 opponent in Sunday's draw, in which they will be unseeded.
