Messi blew a gilt-edged opportunity to seal victory when he missed a second-half penalty, with the Group D match ending 1-1 after Iceland’s Alfred Finnbogason cancelled out Sergio Aguero’s opening goal.
It was a major embarrassment for the two-time world champions and raises questions about their ability to claim football’s biggest prize for the first time since 1986.
As a cigar-puffing Diego Maradona looked on at Moscow’s Spartak Stadium, Messi also failed to respond to his rival Cristiano Ronaldo’s hat-trick for Portugal against Spain a day earlier.
Messi is yet to win a major international tournament and time is running out with his 31st birthday looming.
But Sampaoli said Argentina would regroup, beginning with their next match against Croatia in Nizhny Novgorod on Thursday, and move on from the Iceland disappointment.
“There’s a certain amount of frustration when you come to win a game and don’t get there,” he said. “We were enthusiastic but we played against a structured team.”
He refused to single out Messi for his penalty miss.
“Evaluating Leo’s performance is very difficult because they played almost the whole game in their own half,” he said. “I know he’s committed to helping us get into the next round.”
While the result was not on the scale of that Iceland produced to eliminate England at Euro 2016, it was a major boost for the tiny nation, who retain hopes of advancing from a group that also includes Nigeria and Croatia.
The island nation of 330,000 is the smallest country ever to qualify for the finals but emphatically showed they can mix it with the heavyweights of the game.
“We were playing against one of the best teams in the world, who had the best player in the world,” said goalkeeper Hannes Halldorsson.
“It’s especially important for us because it helped us get a point, which is important for us to reach our goal to get out of the group.”
Iceland’s next opponents are Nigeria in Volgograd on Friday.
– Physical Iceland –
In front of a raucous crowd at the 45,000-capacity venue, Iceland launched into some early physical challenges and rattled Argentina.
They hit on the counter and gave the South Americans a scare when Bjorn Sigurdarson pounced on a loose ball only to rifle his shot just wide of the post.
Aguero settled Argentine nerves in the 19th minute when he latched onto Marcos Rojo’s pass in the box, turned and hammered home with his left foot.
True to form, Iceland fought back and Finnbogason netted the equaliser four minutes later, pouncing after Argentine keeper Willy Caballero parried Gylfi Sigurdsson’s shot for a classic poacher’s goal.
Argentina continued to press but Messi was subdued in the face of the muscular Icelandic defence and the teams went into the break on even terms.
The Barcelona man looked furious as he led his team out for the second half but the Argentines still struggled to make the most of their territorial domination.
They appeared to have secured a breakthrough when Polish referee Szymon Marciniak pointed to the spot after Hordur Magnusson brought down Maximiliano Meza in the 63rd minute.
Messi stepped up for the kick but Halldorsson guessed correctly and palmed away the Argentine skipper’s side-footed effort.
His free-kick in the final moments of the game was deflected off the Iceland wall and the Barcelona talisman trudged off the pitch dejected.
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