Dundee United 3 (Shala 23; Whittaker og 62; Kovacevic 79)
Attendance 24,096
Rangers surrendered a two-goal advantage in this afternoon's Scottish Cup quarter-final tie with Dundee United at Ibrox Stadium this afternoon - and will now have to undertake a replay at Tannadice in ten days time.
When United were last in Govan they suffered a humiliating 7-1 defeat - but there was never any chance of a repeat today.
Manager Walter Smith made one change from Kilmarnock with Nacho Novo replacing DaMarcus Beasley.
The Cup Holders started well with Novo heading just wide from a Kenny Miller cross in ten minutes.
Ten minutes later Miller's surging run following a Darren Dods error ended with a shot that flashed past.
The opening goal however - when it arrive in 23 minutes - came at the other end when Whittaker's error allowed Jon Daly to release substitute Andis Shala through on goal, the German making no mistake.
Ten minutes later Kris Boyd restored parity from the penalty spot after Miller had been upended by United goalkeeper Dusan Pernis as he raced in on goal from a Steve Davis pass. Incredibly Referee Dougie McDonald merely yellow-carded the goalkeeper when clearly it was a certain ordering-off given that Miller was in the process of rounding the Slovakian before being taken out.
The referee had clearly bottled it - but nevertheless Rangers were ahead in 42 minutes when Boyd again slotted a spot-kick home after he himself had been pushed from behind by Shaun Dillon as he rose to meet a Sasa Papac cross.
2-1 behind at the interval, United went all out for the equaliser immediately upon the restart with Craig Conway's dipping shot from the edge of the area following a Shaun Dillon throw-in striking the top of the crossbar.
Within sixty seconds however Rangers had a 3-1 lead when Novo netted with an angled drive from a Lee McCulloh pass.
The tie appeared won - and Boyd almost underlined it with a header from a Davis cross that was held by Pernis in 54 minutes.
A freak goal allowed the visitors back into the game however in 62 minutes when - following a Craig Conway corner - Morgaro Gomis' twenty-yard shot was going well wide when it deflected off Whittaker into the corner of the net.
Kyle Lafferty replaced Boyd seven minutes later and Maurice Edu substituted for Kevin Thomson in 73 minutes.
Miller netted from a Davis pass four minutes later only for linesman Martin Cryans to flag for offside.
That was to prove costly for in 79 minutes the scores were level when following another Conway corner Shala's header struck the underside of the bar - the ball falling perfectly for Mihael Kovacevic to nod home the equaliser.
Ibrox was stunned - and although Beasley replaced Novo in 84 minutes there would be no more scoring and Rangers must travel to Tannadice on 24th March.
Afterwards Assistant Manager Ally McCoist lamented:
"I am disappointed. We should be finishing games off when 3-1 ahead. We didn't play nearly well enough. It's the second time we have lost three goals in the Cup - by our standards that's not good enough."
RANGERS McGregor; Whittaker, Weir, Wilson, Papac; Davis, McCulloch, Thomson (Edu 73), Novo (Beasley 84); Boyd (Lafferty 69), Miller
UNUSED SUBS Alexander, Little
DUNDEE UNITED Pernis; Kovacevic, Dods, Kenneth, Dillon; Swanson (Robertson 52), Gomis (Sandaza 75), Buaben, Conway; Daly, Casalinuovo (Shala 3)
UNUSED SUBS Watson, Banks
REFEREE Dougie McDonald