When Don Robertson blew for kick-off, a plume of smoke so dense hung over Hampden it obscured the entire pitch from view.

As his whistle sounded again 90 minutes later, the difference between Celtic and Rangers could not have been clearer.

Ange Postecoglou has built a winning machine at Parkhead, and on Sunday he manoeuvred it into Hampden to conquer his team’s greatest rivals once again. Five times in a row now has the Celtic manager emerged victorious in this fixture, and now only Inverness Caledonian Thistle stand between him and treble.

The Premiership title is all-but Celtic’s, and here they extinguished Rangers’ last lingering hope of a trophy with a performance that, although rarely sparkling, encapsulated why they are consistently reigning supreme in Glasgow.

Postecoglou’s team has match-winners, players you can hang your hat on turning up for these days and leaving their mark on it. Jota was the hero on Sunday, but it can be any one of them on any given day.

Rangers, meanwhile, have become perennial nearly men. You could not fault their endeavour in trying to find a way past Postecoglou’s side, but they badly lacked the quality and clinical edge needed to do so.

Celtic will return here on June 3 as overwhelming favourites to lift the Scottish Cup. This was not a classic semi-final by any means, but the history books do not care for such details, and neither did the tens of thousands in green and white who lapped up every second of victory.

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This is, though, one of the few fixtures in world football where the frenzied atmosphere can mask the fact there is very little happening on the pitch. Above the din, you could just about hear the game screaming out for some quality.

So frantic was it that even Callum McGregor found himself robbed of possession twice in the opening 20 minutes. But where pockets of football did break out, Celtic had slightly the better of them.

Only once in the first-half did Rangers elude their press without having to go long down the flank, and when they did muster some midfield possession it was either too pedestrian or too loose. Time and again Celtic forced their rivals back to Allan McGregor to punt it either out the park or up towards a statuesque Alfredo Morelos.

It was 45 minutes to underline the critical difference between these two teams.

Rangers were functional but fairly middling, passing in front of their opponents without looking likely to go anywhere, something not lost on Celtic who seemed content enough to let them huff and puff.

This Rangers team have, after all, always had a moment of self-destruction in them. The abdication of responsibility that led to Celtic’s opening goal was one of their most egregious yet in this fixture. And what Celtic have that they do not, is that abundance of difference-makers.

Jota’s header beyond McGregor was the only clear cut opportunity of a mostly poor half of football, yet it was all Celtic needed. It was a simple finish for the Portuguese, but it was made so straightforward by Daizen Maeda’s excellence.

Rangers’ criminal lack of concentration presented the winger with a chance to clip a delightful ball to the back post, where he knew someone would be waiting to pounce. At the other end, more than once did Borna Barisic cross into dangerous to find that Joe Hart was the only person interested in meeting his delivery.

It was the perfect example of forward players who can be relied upon to pull moments of quality from the stuffiness and hustle and bustle of these contests. The contrast with Ryan Kent’s contribution in a blue shirt is almost too on the nose to mention, but if there was ever anything to summarise why Celtic have wrestled back dominance of this city’s eternal rivalry it was this.

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Jota provided the decisive moment of the game, despite being out injured for weeks and managing barely an hour on the pitch. Kent was hooked at half-time to essentially bring his Rangers career to an end. No sooner had the out of contract winger completely switched off moments prior to Celtic’s goal did Beale signal for Fashion Sakala to prepare himself for action.

Jota, meanwhile, was off celebrating another pivotal derby contribution. Two players, two moments to define why Celtic will likely complete a domestic clean sweep by season’s end, and Rangers will finish empty-handed and staring a daunting, expensive rebuild in the face.

That being said, this was no stroll for Celtic in the second period. The introduction of Sakala did, at least, give Rangers some forward thrust and intensity to make their rivals sweat.

Postecoglou’s side have a deserved, hard-earned reputation for playing sparkling football, but perhaps indurated is their ability to simply get the job done in these games. There is a steeliness about them, the kind you need to consistently drive over the line in these huge games.

Rangers threw everything they had at them as time wore on, and should have scored when Sakala somehow skewed an effort against the side netting when presented with an open goal. James Tavernier’s shot cannoned off the post and into the winger’s path, and so certain did his team-mate look to score that a not inconsiderable number of Rangers were already off their seats in celebration.

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Supreme talent and an iron-clad winning mentality Celtic may have in spades, but it certainly doesn’t hurt to carry a hint of fortune along the way. Not only does this win carry them into another Scottish Cup final, it lands another psychological blow on a Rangers team who threw the kitchen sink at Celtic and still came up short.

The Ibrox side will have departed the national stadium with a distinct feeling of having smashed their heads against a brick wall for 90 minutes, and all of it proving to be for nothing. No matter what they try, they simply cannot land a serious blow on their rivals at the moment.

For Celtic, it will have been deja-vu of the best kind, for this is currently a rivalry where one team finds ways to win, and the other finds ways to lose.