Ryan Naderi struck the winner at Hampden to book Rangers a place in next month’s final against Hibs, with Ferguson admitting he could feel the tension building as the game remained goalless.

The former Ibrox captain believes defeat would have brought intense scrutiny on McInnes and his new-look squad, but was impressed by the way they handled the pressure.

Writing in his Daily Record column, Ferguson said: “Make no mistake, what happened at the weekend might be looked upon as a season-defining moment.

“Had Aberdeen nicked it then everything Derek is working so hard to put in place would have been rocked from the ground up.”

Ferguson feels Rangers demonstrated a mentality reminiscent of successful Ibrox sides by refusing to panic as the prospect of extra time loomed.

“They stood up to the situation and found a way of getting through it,” he said. “And that’s the stuff that successful Rangers teams have always been made of.

“There’s still work to do. But, week by week, challenge by challenge Del and his team are getting there.”

Rangers then received another boost when Celtic suffered a 2-0 Premiership defeat at Falkirk the following day.

The result has given McInnes’ side an opportunity to crank up the pressure in the title race, with Ferguson adamant Rangers must now address their recent problems away from Ibrox.

He added: “Rangers are back breathing down their necks. Or at least they will be if they can win at St Mirren on Saturday night to cut the gap to just a single point.”

Ferguson believes victory in Paisley would allow Rangers to apply further pressure before Celtic host Kilmarnock, but warned that the cup final cannot become a distraction.

“They have given themselves a shot at the first silverware of the season, and that’s great,” he said. “But now they have to send out a message that they won’t be satisfied with lifting just one trophy between now and May.”