That certainly didn't look like being the case at half-time as we trailed 2-1, despite Gary Teale giving us an early lead. However a, a Steven Thompson double either side of a Nigel Hasselbaink penalty saw us through despite a late scare.
That means it's now 12-and-a-half years and seven competitive games without defeat against Morton and, for once, means we've managed to avoid a cup exit to a lower league side.
After Saturday's win over Hibs there was just one change to the Saints line-up, the suspension free Hasselbaink taking over from Kenny McLean. And we went in front after eight minutes, Teale cracking home his first Saints goal with a superb free-kick.
Most teams should go on and win from there - but it's never that easy when it's Saints. Sure enough, eight minutes later Michael Tidser played a quick one-two with Peter MacDonald before running through the defence to equalise. Things got worse before the break, MacDonald cutting in before curling a shot past Craig Samson.
We needed to react after the break - and did so 10 minutes into the second half, Hasselbaink skipping down the wing before setting up Thompson to equalise.
Five minutes later we were back in front, Hasselbaink scoring from the spot after he'd been sent flying by a home defender, and it wasn't long before the lead was increased as Jereon Tesselaar crossed for Thompson to head in his second and our fourth.
Again, that should have been that but Hasselbaink took a hamstring knock and had to be replaced by Jon McShane. Unsurprisingly, Morton mounted a cavalry charge - although McShane and Thompson went close to getting a fifth - and they got one back with 10 minutes left, sub Andy Jackson scoring.
You'd probably have put the mortgage on the game going to extra-time after that but thankfully we held on and can look forward to the third round tie while revelling in another derby win.
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