Scotland let themselves down on "an embarrassing night" as they were relegated to Nations League B, said midfielder John McGinn.

Steve Clarke's side held a 1-0 lead over Greece following Thursday's first leg in Piraeus, but were outplayed and outclassed by the visitors in Sunday's return, falling to a 3-1 aggregate loss.

Giannis Konstantelias swept home the opener having been left completely unmarked in the Scotland box before 17-year-old Konstantinos Karetsas curled a second just before half-time, having also been left alone in the penalty area.

The interval was much needed for the Scots, a chance to regroup and clear scrambled heads, but they shipped a calamitous third just 13 seconds after the restart - Christos Tzolis profited after Ryan Christie gave the ball away - and from there, the result was never in doubt.

"It's an embarrassing night for us, everyone is flat in the stadium, we let ourselves down," McGinn said.

"No threat in behind, probably too easy to pick up. Greece deserved to win."

With two World Cup qualifiers against Greece to come this autumn, the play-off was a chance for Scotland to make a statement as well as maintaining their top-tier Nations League status.

Instead, it was Ivan Jovanovic's side who put a proverbial marker down with a dominant performance.

"Greece were just a better side, we had no answer for them," former Scotland defender Willie Miller said on Sportsound.

"We had no creativity and no threat, we didn't make it difficult at all for Greece. It's League A we wanted to be in and we failed tonight."

The boos on the full-time whistle highlighted the feeling among the Tartan Army, but Clarke backed his team to put the disappointment behind them.

"We've had a decent run," he said. "This is a bump in the road.

"If there's one thing I've learned over my time in charge of the national team, it's that there are bumps in the road. It's how you react to it.

"We have to react to this one and make sure that, come June, we know what we're trying to address, and come September, we know what we're trying to do, which is qualify for a World Cup."

The first place to start is with the goals Scotland conceded. The marking for the first two goals was fairly non-existent and the third was a calamity of errors.

Christie's slack pass to give the ball away and then the flat-footed defending that allowed Tzolis to run on to Konstantelias' deft reverse pass.

"The goals are so disappointing on our behalf and we didn't create enough either," midfielder Kenny McLean said.

"To work so hard to get into the position we were in and kind of throw it away there is really disappointing."

Scotland lacked any kind of threat in behind, struggling without the injured Ben Doak's pace, and after a couple of early chances for Scott McTominay they struggled to create anything of note.

"There were players on the pitch playing it a bit safe, playing a sideways pass when what's needed and what everyone in the stadium wants is the ball played forwards," former Scotland striker Steven Naismith said.

"It's tough to do it in an environment like this but that's probably the wee bit we lacked."

"As good as Thursday was, it was as bad tonight," ex-Scotland forward James McFadden added. "A real sore one to take.

"Greece looked really comfortable. We didn't have enough performers. Too many players were well off their best."

After Thursday's first-leg loss, Greece boss Jovanovic made six changes to his starting line-up, including a start for Karetsas.

With an average age of 23 years and four days, it was the second-youngest team named in this edition of the Nations League, and the youthful talent came to the fore.

PAOK winger Konstantelias, 22, had a hand in all three goals, setting up the second and third after smashing the first beyond Craig Gordon.

But it is Karetsas who will take the headlines. He scored the pick of the goals and looked so at ease in the international arena.

"For 17 and what he's doing, the goal tells you… He isn't rushing it and blasting it," Naismith said. "He's got the composure.

"As a coach, these are the types of players who are really hard to find, willing to be aggressive and go forward. His first thought is to play forward and beat his man rather than be safe.

"He influenced the game on Thursday and tonight, that's the sign of a very good player."

The Genk attacking midfielder, who played off the right at Hampden, only made his club debut at the end of last season and has established himself as a regular in Belgium this season before making his international bow in the first leg.

"He's been class, picking up really good positions, comfortable in possession, and made great decisions as well," McFadden said when the 17-year-old was replaced in the second half.

"It was an incredible finish - we're going to be seeing a lot of this kid going