Cappielow is a ground tailor made for cup ties and cup shocks and there was certainly no shortage of confidence here from the current Morton team.
The fact that they had not defeated last night’s opponents for 32 years did not weigh heavily on their shoulders and they took a merited lead after only 11 minutes.
Peter MacDonald can claim an assist for the through ball but Stephen McManus got himself in a tangle as he attempted to clear and the ball deflected off him and into the path of Samuel, who did not need to break stride before lashing it into the roof of the net from 12 yards.
Motherwell were confined to shooting from long range and, although Joe Chalmers and Marvin Johnson both went close, goalkeeper Derek Gaston had little to be concerned about.
Morton’s Conor Pepper was booked for a cynical foul on Johnson but the visitors had recorded only one effort on target during the first half but Motherwell manager Ian Baraclough kept faith with his under-achievers, sending out the same 11 players after the break.
Yet it was the hosts who came close again when MacDonald’s swerving drive from a short free-kick by Ross Forbes was pushed on to his near post by Connor Ripley. Josh Law, yellow-carded earlier, could have been sent off for another foul on Samuel but Morton continued to excel and it required an excellent save from Ripley to deny Tidser.
However, with seconds remaining, substitute Scott McDonald was in the right place to convert a cutback from Lionel Ainsworth and take the tie into extra time.
Samuel struck again, driving Denny Johnstone’s pass low behind Ripley, a goal which prompted crowd trouble in the Motherwell end of the ground which may lead to punishment from the SFA.
Tidser grabbed what proved to be the winner from Bobby Barr’s cross, rendering Louis Moult’s late reply irrelevant.
Morton: Gaston; Kilday, O’Ware, Gasparatto, Pepper; Tidser, Miller (Lamie 86), Forbes, Sabajo (Barr 100); MacDonald (Johnstone 76), Samuel. Subs not used: Adam, McKee, Scullion, Stevenson.
Motherwell: Ripley; Law, Kennedy, McManus, Chalmers; Grimshaw; Johnson, Leitch, Taylor (Ainsworth 81), Thomas (McDonald 57); Robinson (Moult 57). Subs not used: Samson, Laing, Lasley, Clarkson.