Back in March, when there were calls for Stephen Kenny's head following the Luxembourg debacle, the message from the FAI top brass was that the manager would be judged on progress from then to the end of the year.

This was another game to support the view that improvement has clearly taken place and the only rational argument at this stage surrounds the scale of it.

Just like their first encounter with Portugal, Ireland will come away with some regrets, with real incisiveness in the final third eluding them against the stodgy top seeds, who were down a man for almost a quarter of an hour, including injury time when Pepe’s sending off delighted an already energised home crowd.

Ireland weren’t quite capable of capitalising on that weakness, yet there was a confidence about the organisation and identity within their new system that reflected the evolution of Kenny’s team and will earn him a longer crack at the job barring a calamity in the Luxembourg rematch on Sunday.

The positive response from the stadium was an endorsement of Ireland's approach, a reflection that they are an enjoyable team to watch – although the travails of Cristiano Ronaldo were equally entertaining to the masses.

From a neutral perspective, this was a cagey affair of few chances but through Irish eyes, there were visible signs of progress from September's visit of Serbia, where the team was pulled apart regularly by a slick opponent.

Members of the Irish staff feel Portugal are an easier side to play against and there was evidence of that here, with no real fluency to their attacking movements. Bar one block from Seamus Coleman - selected in place of the injured Andrew Omobamidele on the right of the back three - the nerviest moments for the hosts revolved around the defending of crosses into the area. Gavin Bazunu was doing more sweeping than saving.

Portugal did look like a team caught in a dilemma about the structure of this week, with Fernando Santos sending out a clear message by leaving out five of the six players that were one caution away from missing their defining showdown with Serbia.

With Danilo, better known as a midfielder, reverting to centre back next to 38-year-old Pepe, the sense lingered throughout the half that Ireland could pose their guests problems.

And as the interval approached, they got more joy in that regard. Kenny had opted against including Adam Idah, instead deploying Callum Robinson as a number nine with Chiedozie Ogbene coming in for a first competitive start to join Jamie McGrath in the front three. The story of Ogbene's first 45 almost ran in tandem with the Irish display, as he was slightly tentative at the outset, and fell foul of the fussy match officials, before growing in confidence.

His header over the bar from a Robinson cross just before the half-time whistle was Ireland's best opportunity in general play.

At times, the movement just wasn't sharp enough to pull Portugal out of shape, with their savvy defence not as generous as the Qatari side which visited Dublin last month.

McGrath, Ogbene and Robinson did have to work hard going the other way and it was noticeable that the excellent Josh Cullen and Jeff Hendrick didn't find themselves isolated like they have on occasion through the autumn.

Ogbene’s driving run direct from the tip signalled his determination to go up a gear for the second half, and he began to make his presence felt in his duel with Danilo, with the PSG player eventually booked for a mounting foul count.

On the hour mark, Kenny introduced Idah for McGrath to give Portugal’s rearguard an extra pair of speedy legs to think about, a bold move in the sense that it tasked Robinson with greater defensive responsibility. It meant the Selecao had to stay on guard in committing bodies, although they weren’t exactly showing a great tendency to do that.

Their attacks were sparing as opposed to relentless, although the crowd fell silent when Ronaldo rose to meet Andre Silva’s 67th-minute cross, the sighs of relief audible as his header flashed inches wide. It was similar when a right footer 12 minutes later went the wrong side of the post. That was about the extent of the worry, though, even if a few patrons were nervous about the occasional attempts to play the ball out of difficulty.

But Ireland weren’t holding on for dear life, even if their chance count was also low, with Stevens off balance from an Ogbene cross as the punters began to rise from their seat. There was also a half chance for Josh Cullen when the flustered Matheus Nunes lost his balance in the box, the relative newcomer hooked soon afterwards with Santos emptying his bench to introduce Renato Sanches and Joao Felix amongst others.

Ireland kept chipping away rather than taking a step back, and Robinson’s persistence drew a rash hand from Pepe and a second yellow that was almost an identical offence to Ogbene’s dubious booking before the interval. VAR wasn’t going to save him and Portugal’s plan to avoid Serbian damage was up in smoke.

Kenny had already introduced Conor Hourihane and James McClean at that stage, and Will Keane was sent in late in the day to play a part in a disallowed goal but Portugal regrouped to avoid a disastrous collapse and might even have nicked it at the end when Ronaldo broke free to test Bazunu.

But, in contrast to September, it was Portugal waiting for the whistle at the death, happy to get out with a diminished sense of mission accomplished. Kenny is one more performance away from achieving his own longer-term ambition.