Scotland delivered a resolute defensive display to hold Portugal to a goalless draw and secure the first point of their Nations League A campaign.

The Scots passed up a glorious chance in the opening minutes through Scott McTominay and were then starved of possession as the visitors searched for an opener.

Cristiano Ronaldo was frustrated in his attempts to register a 134th goal in Portugal colours on his 200th international start as home goalkeeper Craig Gordon and his defence held firm.

The draw means Steve Clarke's side have now won just one of their past 16 matches, but they avoided the unwanted history of becoming the first Scotland team to lose five straight matches.

After the struggles at the Euros and this Nations League campaign, Scotland needed to give the Hampden crowd something to feed off and had a massive chance to do that just four minutes in.

Ben Doak surged free wide on the left and teed up Andy Robertson to deliver a lovely cross to pick out McTominay completely unmarked in the box, but his header from eight yards out was straight at Diogo Costa in the Portugal goal.

It was the type of chance, against this level of opposition, you simply have to take.

Ronaldo, who broke Scottish hearts when the sides met in Lisbon last month with the late decisive goal in Portugal's 2-1 victory, had his first sight of goal, but his low effort from the edge of the box was comfortably saved by Gordon.

Ryan Christie stung the palms of Costa with a half-volley from the edge of the box, while at the other end Gordon was called into action to claw away a free-kick from Nuno Mendes.

The visitors were dominating the ball and Francisco Conceicao blew a decent chance when he ballooned his effort way over the bar after being teed up by Ronaldo.

Portugal continued to probe away at the Scottish defence without ever looking like stretching the hosts' rearguard to breaking point.

Substitute Lewis Morgan crossed for Che Adams to nod down into the path of McTominay, but the Napoli man could not apply the finishing touch.

A big chance came 15 minutes from time when Anthony Ralston sprung the Portugal offside trap, and with McTominay sprinting into the box in support, a pinpoint cross would surely have brought a goal, but the pass was heavy and the chance was lost.

Gordon produced a big save in the closing moments to deny Bruno Fernandes, and there was one more heart-stopping moment as debutant Nicky Devlin hurled himself in front of Rafael Leao's goal-bound effort to ensure the Scots held on for a point.

Despite losing all three previous games in the group - single-goal defeats at home to Poland and away to Portugal and Croatia - there was enough in those performances to offer hope the Scots could at least compete with the Portuguese superstars on their own patch.

It was not always pretty, but for 90 minutes, competitive is exactly what they were. They created a couple of early openings - the McTominay chance the most glaring - and coped admirably with the speed and movement of the visiting attack.

As the game wore on they saw less and less of the ball, though, as the backline dropped deeper and deeper and Adams up front, selected ahead of Lyndon Dykes, was left battling for scraps or challenging for balls in the air against the comparatively imposing figures of Ruben Dias, Antonio Silva and Joao Cancelo.

As a defensive unit the Scots were organised and resolute and limited their illustrious opponents to very few clear-cut chances. The problem once again was their inability to offer a significant attacking threat.

Teenager Doak had few opportunities to make an impression on just his second international start, and McTominay looked yet again the most likely to provide a goal. With that early headed chance, he should have.

Clarke and his depleted team - shorn of regulars John McGinn, Kieran Tierney and Angus Gunn - simply had to stop the bleeding of recent defeats and this point, against one of Europe's top sides, gives them something tangible for their considerable efforts in this first block of games.

Al-Nassr striker Ronaldo, having scored in each of his country's three previous Nations League victories to take his international goal tally to an outrageous 133, as always looked to take centre stage on his first appearance at Hampden.

He prompted boos from the home crowd as he remonstrated with referee Lawrence Visser, then huge cheers from the Hampden faithful followed as he comically gave the ball away from a free-kick after being clattered by his former Manchester United team-mate McTominay.

On the half-hour mark, the Real Madrid great and Portuguese icon attempted a bicycle kick, only to be penalised for a high boot.

Ronaldo smacked the Hampden turf after sending a header over the bar from 12 yards early in the second half and was then denied by a last-ditch tackle from Grant Hanley as he was ready to pull the trigger having broken into the box.

The greatest scorer in the history of men's international football had one last attempt, slicing wide after dancing inside a couple of defenders, and, with that, his chance to mark his Hampden bow with a goal was gone.

For all their dominance of the ball, Portugal were wasteful in the final third. But with three wins and this draw in their Nations League campaign so far, boss Roberto Martinez is unlikely to be too concerned with one off-night in front of goal.

Scotland head coach Steve Clarke: "It's not about turning a corner, it's just about working hard and not letting the country down. The point was important for us after the work the group put in to get off the mark.

"Defensively sound. The shape of the team was good. We denied a lot of space in behind. Good concentration in the box, determined defending at times, some really good blocks, which you need against sides like Portugal. Everyone contributed to earn the point.

"Everyone keeps talking about confidence, but they know they can play well. We maybe didn't play as well as we could on the ball, which could be down to fatigue. But I don't think they lack confidence."

Portugal head coach Roberto Martinez: "Steve Clarke is building a national team that looks like a club and that's a big, big compliment.

"Everybody works for each other, they know the structure. They're brave when they have to be, they've got quick attacks.

"Full credit to Steve Clarke and the technical staff, they're doing a great job."