Celtic came from behind to deny Rangers a third straight victory over their rivals as Adam Idah's second-half strike frustrated Barry Ferguson's home side in the Scottish Premiership.

Nicolas Raskin had an early header ruled out for offside before Cyriel Dessers netted his 25th goal of the season for Rangers just before half-time, only for Republic of Ireland international Idah to pounce and level.

The draw means Rangers have failed to win at Ibrox for the seventh straight fixture, an unwelcome run that has never happened before.

For Scottish champions Celtic, the point allows them to retain their 17-point margin over the second-top Ibrox side as they close out another successful league campaign unscathed.

With nothing at stake and the title decided, the idea this was meaningless remained fanciful.

After conceding three goals in each of their last three meetings with Rangers, and starting slowly in those, Celtic manager Brendan Rodgers emphasised to his team the need to begin strongly.

They didn't. Within a minute, Leon Balogun met a corner with a free header but clipped the crossbar to Rodgers' relief.

Being alert at set-pieces was something the Northern Irishman cited pre-match having seen that cost them in recent match-ups, but they struggled with that at times.

The visitors grew as the first half went on, though, and after Idah failed to play in James Forrest, Vaclav Cerny came close via a deflection, but visiting goalkeeper Viljami Sinisalo did superbly well to retreat and tip over.

It was frenetic. Another set-play looked to have undone the visitors when James Tavernier's deep cross was met by Raskin and his header crept home. Celebrations were curtailed by a VAR check that deemed him just offside.

It swung back and forth. Cameron Carter-Vickers had a header tipped on to the bar by Liam Kelly. Rangers' goalkeeper also did well to stay big when Idah got clean through.

Almost immediately, Rangers broke, Cerny dummied brilliantly and Dessers did the rest, holding off Liam Scales before finding the corner. Twenty-five goals for the season is not bad for someone who draws such a frequent high level of criticism.

Celtic had answers to find, as they have of late in these meetings, but they found the right one.

Daizen Maeda escaped down the left. The ball eventually fell to Idah, who turned brilliantly and slammed home via a deflection.

The drama continued as that was called offside, only to be overturned as Maeda was not interfering with Kelly's view as the ball hit the net, despite being offside.

Maeda uncharacteristically failed to capitalise on a late break, but Celtic were perhaps still the happier to leave Ibrox unscathed with the title already delivered.

After six home games without a win, a seventh against Celtic was unthinkable, especially after conceding this league so tamely.

One goal in those six games was an incredibly poor return. That may have been the spark for a quick start in which Balogun was close to an immediate opener.

On the big occasions this season, Rangers have often found a higher level of performance and loosely dropped points and trophy opportunities elsewhere.

They produced another one here but could not see it through to deliver a little more respite for their suffering supporters.

For interim head coach Ferguson, it must have seemed likely that this would be his last chance to put one over on Celtic as the man in charge. He could not quite get there but will likely feel his side performed well over the piece.

It is a season Rangers just want done with, with hope of better times ahead on the horizon once the takeover of the club is finalised.

With a fourth successive Premiership title in the bag, this mattered little to Celtic. Except it did. They all do against Rangers.

Having lost their last two league fixtures against the Ibrox side, there was no chance this would be taken lightly.

Rodgers pointed to starting well and being more alert at set-pieces. Both were missing and they were fortunate more than once not to concede.

However, they responded well and took a grip of matters at times, albeit their opponents had better chances, particularly in the first half.

That they managed to come from behind is a reminder of Celtic's character and self-belief. They were not at their best again, but in this environment, and circumstance, they will surely be satisfied.

For Idah, this game also provided a big moment. His goal return has been reasonable given his minutes on the pitch, and another big one against Rangers will boost the perception of his overall contribution.

Rangers interim head coach Barry Ferguson: "A bit disappointed we didn't come away with three points.

"The commitment from my players was what I asked for, really good.

"Scored a good goal, went in at half-time deserving of the lead. We know Celtic are going to come out [strongly in the] second half, but we weathered the storm really well. It was just that bit of quality in the end that we need to be better at."

Celtic manager Brendan Rodgers: "The performance level was a good one. Rangers changed their structure, we were playing against a diamond, so once we figured that out, we had lots of moments where we played through that pressure well.

"There weren't too many chances either side. Second half, we controlled the game. When you come to Ibrox, you sometimes have 10-15 minutes where you're under real pressure, backs to the wall, but I never really felt that. We got the goal, we deserved it."