Raheem Sterling rolled home a penalty to give England a winning start to the Nations League campaign.
Sterling's 89th minute spot kick proved to be the difference after his initial shot hit the arm of Sverrir Ingason, who was shown a harsh second yellow card as a result.
It would not be as straightforward as they would have hoped as Iceland went straight down the other end and won a spot-kick of their own after Joe Gomez was penalised for grappling with Holmbert Fridjonsson.
Unlike Sterling, however, Bjarnason could not keep his cool and blazed the resulting penalty high and wide of Jordan Pickford's goal.
It came after Kyle Walker was sent off for two yellow cards, with a rash tackle earning him the second card.
Gomez is still only 23 but already has a presence about him. That probably comes from playing alongside Virgil van Dijk at club level. Those two have established a formidable defensive partnership, which was a big part of Liverpool’s success in the Premier League last season.
There was always going to be some doubt, though, as to whether Gomez would perform at the same level without Van Dijk.
Gareth Southgate can rest easy, though. Gomez was dominant, almost casual against an Iceland side that barely had a look in from an attacking perspective. He mopped up every lose ball, played out from the back with ease and generally looked like the top class player he has become at Liverpool.
There was a heart in mouth moment late on when he conceded a late penalty, moments after Raheem Sterling had converted from the spot at the other end. But that proved to be a minor - and, thankfully, not costly - blip on an otherwise impressive night for the defender.
Gomez, on the basis of this performance, looks set for a long and successful England career.
Playing at left-back, Trippier was steady and didn’t look out of place. It was evidence of his versatility, his value in a squad not short of talented full-backs.
Whether Southgate will want to continue with the Atletico Madrid man in the position remains to be seen, but he will be pleased to know he has that option.
Trippier, having played commendably in an unfavoured position, will fancy himself to challenge again for the right-back place, too.
Walker’s sending off has opened that space up for the Denmark game, and Trippier is well placed to take advantage.
It’s no coincidence that all of the winners were in England’s back five. Iceland nullified Southgate’s side in the final third, but did very little at the other end of the pitch.
For that reason, Pickford was largely untroubled, a spectator for much of the game. When he was called upon, he did his job with minimal fuss. There were no unforced errors, no moments of panic.
Southgate clearly trusts the Everton goalkeeper, and with every clean sheet he makes it harder for the boss to leave him out.
There will be tougher tests ahead, but for now Pickford, rightly or wrongly, has the No.1 spot.
The Southampton midfielder is still unproven at international level, making only his third England appearance against Iceland.
And it felt like an opportunity missed for Ward-Prowse. Tasked with creating for his more advanced teammates, the 25-year-old struggled to assert himself on the game, too often playing the safe pass.
His usual prowess from set-pieces wasn’t really on show either, and at times it was easy to forget that he was on the pitch at all. These Nations League games are effectively an audition for some players on the international periphery, so consistency is important.
A forgettable display from Ward-Prowse will likely not have done much to impress Southgate.
It would be harsh and overly reactive to write off Foden after his England debut. But there was definitely a hint of disappointment as he jogged off the pitch in the second half.
He was largely marked out of the game by a disciplined, rugged Iceland team. There was certainly none of the creativity, flair and fluidity we’ve seen so often for Manchester City.
That might have been down partly to nerves, though Southgate will hope to see more from the youngster in future.
Foden will play better than this, of course, but expectations are so high that this performance didn’t exactly inspire.
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Walker started fairly well, driving forward and linking up with Jadon Sancho in the first half. But that soon faded, and the second half was a disaster for the City man.
He was sent off on the 70 minute mark for a second yellow card, a needless lunge that means he will be suspended for the Denmark game. And there’s every chance he might not find his way back into the starting XI for a while now.
Southgate has dropped him before, and the England boss is not short of options at right-back. Trent Alexander-Arnold, Trippier and Aaron Wan-Bissaka are all pushing for a place in the team.
Walker is 30 now, too, no longer a young up and comer. It was a bad day for the full-back, who will have work to do to prove himself again to Southgate.