However, his journey between these two points was far from straightforward. Indeed, arguably the most significant events occurred in the interim, namely at the Copa America Centenario in the United States.
As if that were not enough, although his side failed to retain their UEFA Champions League crown, falling in the quarter-finals, he also lifted the Copa del Rey and Spanish Super Cup.
It was a similar story at international level. After missing the opening four rounds of 2018 FIFA World Cup Russia™ CONMEBOL qualifiers through injury, he was back with a bang in the March double-header, inspiring Argentina to wins away to Chile and at home to Bolivia that left them well positioned in the automatic qualification places.
Then came June and the Copa America Centenario, where Messi caught the eye by showing up with a fledgling, flaming beard that would become not just a permanent fixture, but a sensation among both the Argentinian supporters and his fellow Albiceleste players – some of whom began sporting replicas – to the point that it even took on a talismanic status.
"Things have worked out this way and I'll keep it all the way to the end. I'll just give it the odd trim and touch it up a bit. If I shave it off, they'll kill me," Messi memorably said following the quarter-final victory over Venezuela. That day, the Barça star set up Gonzalo Higuain in sublime style and broke new ground in the process: it was his eighth-ever Copa America assist, a new record for the competition.
Yet, more history was to follow in the semi-finals against hosts USA, when Messi curled home a stunning free-kick to establish himself as Argentina's all-time top scorer, surpassing 44-goal Gabriel Batistuta. At that stage, it looked for all the world like the tournament would yield a long-awaited, elusive senior international trophy that would go some way towards exorcising the demons of the final defeats at the 2014 World Cup in Brazil and the 2015 Copa America in Chile. "This group of players deserves it," he said after the semis.
Hammer blow and retirement
Seemingly weighed down by the pressure, Messi failed to make his mark over 120 minutes in the final against Chile. But the worst was still to come: he subsequently missed from the spot in a gut-wrenching penalty shoot-out loss. It was small wonder, then, that he cut a disconsolate figure in the immediate aftermath, and his decision that he could not take any more international heartbreak was understandable.
"That's it, my national-team career is over," he announced in the mixed zone, "I think it's in everyone's best interests. I've tried so hard to be a champion with Argentina. Unfortunately, it wasn't meant to be and I leave without having achieved it."
This bombshell sent shockwaves around the football world and, more importantly, sparked a reaction from the Argentinian fans, not to mention several high-profile figures. Suddenly, the criticism – which had questioned his leadership skills and asked why he could light up finals for Barcelona but not for his country – gave way to a groundswell of affection and appreciation. Campaigns were launched on social media urging him to reverse his decision, many of which went viral.
Messi, for his part, gave off mixed signals. In one of his first public appearances after that fateful final, he caused a stir with his bleach-blonde hairdo, a first for him. He would go on to explain that he had needed a change following the "madness" of what had happened, calling it a "fresh start after losing the Copa America on penalties again".
Retirement and end-of-year euphoria
No sooner had he taken over from Gerardo Martino than new Argentina coach Edgardo Bauza also set about trying to change the little magician's mind. His efforts proved successful. Swayed by the shows of unconditional support, a revitalised Messi released a statement announcing his return to the international fold: "A lot of things ran through my head on the day of the [Copa America] final and I seriously considered quitting, but I love my shirt and my country too much. I'd like to thank everyone who wanted me to keep playing for Argentina."
So brief was his hiatus that Messi did not actually miss any matches in the interim, and he marked his first international appearance after the saga in trademark fashion by notching the winner against Uruguay.
However, the attacker's importance to La Albiceleste was laid bare for the umpteenth time when he was forced to sit out the following three qualifiers through injury. Argentina mustered a mere two points from a possible nine in his absence, being held to draws in Venezuela and Peru before being beaten at home by Paraguay for the very first time.
His latest international comeback, in time for the double-header in November, was accompanied by yet another new look: the tattoos on his left leg had been almost entirely blacked out. The mood was similarly dark following the 3-0 humbling by Brazil in Belo Horizonte, where Messi put in a muted display. However, with the alarm bells ringing, he responded emphatically with a goal and two assists in a win by the same scoreline against Colombia, a result which ensured that Argentina would end the year in the play-off berth in the South American qualifying standings.
After going back to his natural hair colour, Messi fittingly proved that he is back to his vintage best in the Catalan derby, in which he dazzled and scored the last of his 59 competitive goals in 2016 (51 for Barcelona and eight for Argentina), a tally that made him the calendar year's top marksman for the third time in his career.
Having been as inspirational and decisive as ever for both club and country, it is no surprise that Messi is one of the three The Best FIFA Men's Player 2016 finalists, even if his year was anything but plain sailing.