THE arrival of Barcelona in flamboyant form at an English stadium in early spring has become almost an annual Champions League highlight.
Mostly, the tie ends with the Premier League side second best, then gazing with awe and envy at Catalonia's home-grown excellence.
But the last sobering recital by a representative of Barca had a different context: Wembley, in November. England 0, Chile 2.
Alexis Sanchez scored both, exhibiting his all-round striking qualities, the first goal a stooping header, the next a cool chip as he confronted Fraser Forster.
Barcelonistas would recognise the second strike as most characteristic, and lately they have started to really trust Alexis – he wears his first name on the back of his jersey – when he engineers his way into those one-on-one duels.
He is on a roll, with six goals from his last six starts, and Barca's leading scorer, with 15, in La Liga.
This is Alexis' third season at the Nou Camp and by far his best. During his first 24 months he encountered a scepticism which typically greets those who arrive there for substantial fees but without megastar billing.
At a club whose 21st-century successes have been dominated by footballers brought up through the club's La Masia academy – as Lionel Messi and eight or nine other regular starters were – being an outsider only carries privilege if you make a fanfared entrance and quickly demonstrate world-class capabilities.
Ask Zlatan Ibrahimovic, who had a red carpet rolled out for him but grumbled when it became plain Messi would be the team's tactical focus.
Or Thierry Henry, who initially found Barcelona, who had pursued him for several years, less inclined than Arsenal to shape their game plan to what he saw as his most productive skills. As for Alex Song, just don't ask.
Ask Yaya Toure, who spent three years at the Nou Camp, and the answer is more nuanced.
Tomorrow, when Toure lines up for Manchester City against the club he left for the Premier League in 2010, he will be warmly greeted by former team-mates with whom he shared many triumphs, and by the player, Sergio Busquets, who effectively superseded him.
Busquets will prepare for 90 minutes of muscular confrontation, in the centre of midfield, and also ready himself for a Toure who behaves more adventurously in sky blue than he used to in cherry and blue.
Toure joined Barcelona in 2007, the year before Pep Guardiola became head coach there, delivering a sweep of prizes.
"He was really important for Barca," says Gerard Lopez, a former Barcelona and Spain midfielder, and La Masia scholar, who had played alongside the Ivorian at Monaco.
"It was a combination of things that meant he left when he did."
One was the handsome fee – close to €25m offered by City for a player who had cost Barca €10m.
The other was the rapid rise of Busquets, schooled since childhood in the 'Barca Way' and elevated from the youth ranks by Guardiola, who identified in Busquets' greater positional discipline and a finer understanding of how and where on the pitch Guardiola wanted Barcelona to press opponents.
But watching Toure for City, as Gerard Lopez acknowledges, causes pause for thought over how Barcelona used him.
Toure used to launch his safaris from centre-circle to opposition penalty box for Barcelona, but much less often than he has done for City.
Compare his 15 goals across all competitions this season with the half a dozen he scored in 117 games for Barca. There, Toure smiles, he was never invited to take free-kicks – so lethal over the past six months – because a queue headed by Ronaldinho, then Deco, Xavi or Dani Alves, and, later, Messi would gather ahead of him for every dead ball.
Tactically, Guardiola had Toure designated as anchor midfielder, almost always in a 4-3-3. In two of his biggest Barca games, the Champions League semi-final and final of 2009, Toure did emergency service at centre-back.
That sort of versatility was prized and praised, though ultimately Toure was deemed expendable. Similar qualities of versatility are cited by Barca's coaches of Sanchez.
The Chilean (25) can operate wide left, as a mobile central striker, or wide right, they nod approvingly.
But versatile is not quite the same as multi-faceted, which is how to-the-manor-born players such as Andres Iniesta or Cesc Fabregas are lauded.
Sanchez, signed from Udinese in 2011 after two stand-out years in Serie A, has not attained that status.
Even in his current form, he is reminded he must work on chiming his runs with Barca's established patterns, and that despite his run of goals, he cannot be guaranteed to be picked ahead of, say, the winger Pedro in an XI where Neymar and Messi are both fully fit.
Alexis would have noticed during the spectacular 90 minutes against Rayo that Neymar's entry from the bench, Pedro's exit and Messi's two goals all received louder ovations than his fine contributions.
Alexis's longer-term future may turn out a little like Toure's. He is coveted abroad, notably by Juventus. And a number of Premier League clubs would find it more than tempting if Barca made him available at a price that showed a decent profit on the €26m they paid Udinese.
His profile is rising, and could step up further at a World Cup where he is the focus of his side's attack.
England can testify to how potent Alexis looks with Chile. (© Daily Telegraph, London)