Rangers needed a controversial late equaliser to claim a 1-1 draw with Albion Rovers as the League Two minnows came close to a Scottish Cup shock at Ibrox.
The part-timers had stunned the home fans as Ciaran Donnelly fired them into a 13th-minute lead in their quarter-final tie against the Glasgow giants, who are unbeaten in all competitions since August 3 last year.
Rangers piled on the pressure in the second half but were left frustrated by the resolute defending of a side that sit seventh in Scotland's bottom tier until the 78th minute when Bilel Mohsni knocked Lee Wallace's deep cross past Neil Parry to end their hopes of a giant-killing.
However, the goal left the Rovers management team incensed as they felt the French defender had fouled the 'keeper as he went to claim the cross.
The two sides will now have to do it all again in a replay at New Douglas Park on March 18 as they bid to meet Dundee United, who defeated Inverness Caledonian Thistle 5-0, in the semi-finals.
St Johnstone will take on Aberdeen in the other last-four match.
"For 70-odd minutes we weren't going to still be in the cup but we got the break and kept going and got the goal," said Rangers manager Ally McCoist.
"I thought Albion Rovers defended very well but on pressure we certainly deserved to take something out of the game."
Albion manager James Ward didn't want the equaliser to take the shine off a fantastic result for his club.
"It's a goal and there's nothing I can do to change that and I don't what to dwell on it as I think the sole focus should be on the quality of the performance. I have been saying all week to people that we were capable of winning and I think everyone didn't believe me," Ward said.
Albion named the same side that knocked Scottish Premiership side Motherwell earlier in the competition and they showed no signs of being overawed by the occasion as they threatened the Rangers goal with under a minute on the clock.
Mark McGuigan thundered forward and found Liam Cusack at the edge of the box but Cammy Bell watched his first-time effort go wide.
- Donnelly's first goal of season -
And it was part-timers Albion who stunned the home crowd in the 13th minute when Donnelly grabbed the opener.
Lee McCulloch's wayward defensive header from a corner fell to the Albion Rovers captain who fired past Bell from close range for his first goal of the season.
Rangers immediately responded with Templeton sending a header on to the roof of the net before Parry made a fine save to deny Daly whose header from a Lee Wallace free-kick looked to be seeking in.
A sustained period of pressure saw Rangers press for an equaliser just before the break. Templeton saw his fierce strike blocked as Rovers players threw themselves in front of the ball before Parry stopped Shiels' shot on the line.
Rangers had a great chance to haul themselves level seconds after the restart. Fraser Aird's corner was headed down by Mohsni to McCulloch but the Rangers captain hooked his shot wide.
The frustrations of the home fans increased in the 50th minute when the ball broke to the unmarked Daly in the box but the Irish striker somehow sliced his effort wide of the target.
The pressure continued to mount on the Rovers goal with Daly's next effort on target but Parry made the save and the danger was cleared before Nicky Law could pounce on the rebound.
Templeton thought he had finally made the breakthrough in the 63rd minute after he sweetly connected with Richard Forster's cross but his shot clipped the top of the crossbar on its way over.
Michael Dunlop was inches away from an own goal as he turned Aird's fiercely whipped in cross just round the post before Mohsni's long-range effort was tipped over the bar by Parry.
Rangers boss Ally McCoist replaced Daly with Sebastien Faure in the 74th minute as he threw Mohsni forward and his decision was vindicated three minutes later when the Frenchman grabbed the equaliser.