Celtic the real acid test for Rangers in Scottish Cup semi-final

Rangers and Celtic have gone through considerable change since their last meeting

It's been a shade over 13 months since Rangers and Celtic last met - in the League Cup semi-final at Hampden on 1 February 2015.

Not that long ago in terms of time but a relative eternity in the lives of these two clubs.

That semi-final was the strangest kind of procession for Ronny Deila's team. On the face of it, a 2-0 victory might suggest that it was relatively close, when it was not.

A two-goal deficit might hint that the gap between them at that point wasn't that large, when, in reality, it was.

Everybody knew the score. Rangers avoided a humiliation, but there was no denying the difference in class and feel-good. The clubs were worlds apart.

Now that the sides have been drawn together in the semi-final of the Scottish Cup, back at Hampden in mid-April, the starting pistol has sounded on the countdown. It will be exhaustive, as ever.

When the draw was made, you didn't know what to reach for first - the telephone or the tin hat. Both will be useful in the six-week build-up to this thing.

Celtic defeated Rangers 2-0 in last season's League Cup semi-final

While Glasgow football's own version of a Victorian Odditorium begins to unfold, it's safe to say that the managers of the three other clubs left in the draw will be relieved.

Mixu Paatelainen, of Dundee United, will be left in relative peace between now and then to focus on trying to perform a grand feat of escapology from the foot of the Premiership.

His team will face either Alan Stubbs' Hibernian or John Hughes' Inverness Caledonian Thistle, who drew on Sunday and will replay on 16 March.

Paatelainen and one from Stubbs and Hughes will have a low-key journey to their own semi-final compared to Deila and Mark Warburton.

As the semi-finals approach, they may gripe a little about not getting the same profile as Rangers and Celtic, but they surely won't envy Warburton and Deila and the unending circus they are about to be pitched into.

Quite a lot has changed for Rangers and Celtic since Hampden in February last year, when Leigh Griffiths and Kris Commons scored the decisive goals.

Rangers, in those dog days, were being managed, in the short-term, by Kenny McDowall, a guy who spent most of his brief time in the Ibrox hot seat fumbling around for the ejector button.

Mark Warburton's Rangers are 12 points clear at the top of the Scottish Championship

There was rancour and mayhem off the pitch and confusion and failure on it. In their 10 games preceding the Celtic semi-final, Rangers drew with Alloa Athletic at Ibrox in the Championship and then lost to them in the Petrofac Cup. They also lost to Hearts, Queen of the South and Hibs - on a cumulative score of 8-0.

Ally McCoist had gone on gardening leave. The team that played Celtic had Steve Simonsen in goal with Ian Black, Kyle Hutton and Fraser Aird in the midfield.

After they got beaten by Celtic, their next two games were against Raith Rovers at Ibrox in the Scottish Cup and against Hibs in the Championship, again at Ibrox. They lost both of them.

Then they had a win against Raith Rovers followed by five successive draws - Falkirk, Cowdenbeath, Queen of the South, Livingston and Alloa. Stuart McCall was in charge by then - their third manager of the season.

Celtic, meanwhile, were motoring nicely. Their win over Rangers was of one of eight in a row. That run was only stopped by Inter Milan, in the Europa League knockout stages.

Deila's side drew a thrilling first leg 3-3 at home and were admirable in defeat at the San Siro, their 1-0 loss coming late, despite playing with 10 men for much of the night after Virgil van Dijk's red card.

Stuart Armstrong and Gary Mackay-Steven had just come in from Dundee United. Things looked promising for Deila, but things changed, in both sides of the city.

Now it is Celtic's manager who is unpopular and a little haunted. Now it is Celtic who are faltering in the league and drawing the heat from their supporters. Now it is Celtic fans who are calling for change in ever louder numbers.

Their own team, against Rangers last year, had Van Dijk and Jason Denayer in the heart of the defence where now uncertainty rules.

The midfield had Stefan Johansen, on his way to the player of the year award. Johansen has been a shadow of his previous self this season.

Celtic had Griffiths, but they also had Anthony Stokes and John Guidetti. Now they have Colin Kazim-Richards and Carlton Cole. Kieran Tierney is the one upgrade on 13 months ago.

They have signed vast amounts of players - particularly midfield players - but their policy is unfocused and team is unconvincing. Deila has admitted he doesn't know what his best starting line-up is.

The gap between Rangers and Celtic has narrowed, but until they meet, we won't know what kind of margin we're talking about.

What you can say about the Ibrox club is that the mad turbulence has gone - save for the odd intervention by shareholder and Newcastle United owner Mike Ashley - and that peace reigns.

Warburton has brought authority. He has improved the team in all departments. They haven't had many setbacks this season, but it's instructive to look at what they did after each one.

The wounding 3-1 League Cup loss to St Johnstone at Ibrox in September was followed by five straight wins. November and December were testing months - a loss to Hibs, draws with Livingston and Morton and then another loss to Falkirk had some of us wondering about their mettle - but then they beat Hibs 4-2 and won 11 of their next 13 games and drew the other two.

Warburton has instilled character where before there was huge mental weakness. He has seen off Hibs in the Championship race and, on Saturday, his players thundered past Dundee and into the Scottish Cup semi-final.

They put four goals on Paul Hartley's team, who sit fifth in the Premiership and who had, just three days before, taken a draw, and almost a win, from Celtic Park.

Celtic, and not Dundee, remain the acid test of Rangers' improvement, but the test doesn't look as exacting as it was 13 months ago.

That's the hunch. We'll know more about the truth of that after the craziness of the build-up ends and the football finally begins.