St Johnstone manager Steve Lomas rued his side's failure to convert chances in the Scottish Cup defeat to St Mirren.
Home goalkeeper Craig Samson was on excellent form to prevent Steven MacLean, Rowan Vine, Liam Craig and Nigel Hasselbaink netting.
"It's been our Achilles heel most of the season," Lomas told BBC Scotland.
"We're out the cup because we haven't taken our chances. We could've had five goals with the chances we had."
He added: ""We thought we'd cured that with five goals in the previous two games."
A double from St Mirren's Esmael Goncalves ensured the Perth side went no further than the fifth round.
"I feel very sorry for the fans because we desperately wanted a cup run," Lomas said.
"Goals change games and we should've been going in 2-0 up at half-time.
"You've got to take your chances when you get them."