In November, when Kai Havertz was struggling to convince following his arrival from Chelsea, most Arsenal fans would not have believed you if you had told them how much and how quickly his fortunes, and their perceptions of him, would change.
On Tuesday night, in the aftermath of a 5-0 win over his former side in which Havertz scored twice to send Arsenal three points clear, the Emirates Stadium reverberated to the sound of Shakira's 'Waka Waka', sung in honour of a player emerging as an unlikely hero.
It was quite a scene. The chant has been aired with increasing regularity since his first goal for the club, a penalty at Bournemouth in September. But never with quite this much gusto.
Many doubted him. Mikel Arteta did not. That much was clear in how much he used him even in those awkward early months. Havertz has now featured in all but one of Arsenal's 34 Premier League fixtures. He played in all 10 of their Champions League games, starting nine.
He has been a ubiquitous presence. But in different roles. In August, a debut as Arsenal's centre-forward in the Community Shield win over Manchester City hinted at Arteta's plan for him. Soon, though, he was moved back into midfield. It took him time to adapt.
It took time for Arteta and his staff to figure him out, too.
"We have to do that with every player," he explained to Sky Sports in December. "We can't just have one idea for what we want. In the end, we have to make that position, that role and the demands it has, fit the specific qualities of the player, to empower those qualities."
At the time, it felt like Arsenal had done that. Arteta was speaking days after the 4-3 win over Luton at Kenilworth Road in which Havertz had produced his most impressive performance yet for the club, scoring his third goal in four games from midfield.
But really, his best was still to come. Arteta's willingness to adjust and adapt his team has been crucial in sustaining Arsenal's title charge. It is a trait most apparent in his use of Havertz.
With 11 goals and five assists in the Premier League, he has already produced his most productive season in England by some distance. But the numbers become more impressive when you consider he has only played around 30 per cent of his minutes up front.
Havertz's finishing was held up as a reason Arsenal needed to go all out for a striker earlier this season. Maybe they still do. But, in the context of their campaign, both on an individual and collective level, pushing him into that role has been transformative.
Since his first start there, in the 3-1 win over Liverpool in February, he has scored seven goals and provided four assists in 12 appearances, giving him a combined total second only to Chelsea's Cole Palmer among all Premier League players in that timeframe.
Even during that run, though, there have been four starts back in midfield. Narrow it down further, to the games he has started up front, and it is six goals and four assists in eight.
There were moments of frustration in the win over Chelsea. A pass when he should have shot. A shot when he should have passed. A one-on-one chance sent too close to the goalkeeper. But Havertz's display showed the breadth of his offering in the role.
His first goal was an example of the quality of his runs in behind and his strength as he met Martin Odegaard's sublime pass, held off Marc Cucurella and finished emphatically.
Then, for his second, he demonstrated his knack for finding space in the box, allowing Bukayo Saka's pass to run across his body and rifling a low finish in off the post.
But his goals, well-taken as they were, only told part of the story. Havertz excels in his link-up play and there were plenty of examples of that against Chelsea too.
He was involved in the build-up to the opener, moving into the No 10 position to collect Saka's pass then feeding Thomas Partey. Later, he could be seen doing the same for Leandro Trossard before bursting beyond Chelsea's defensive line to latch onto his return pass.
His former side, like many of Arsenal's recent opponents, struggled to pick him up as he dropped back to connect with team-mates, just as they struggled to manage his runs in behind. To quote Arteta, they are qualities that make Havertz a "constant threat" up front.
"He can threaten you in behind and he can come to some good spaces and provoke a lot of issues positionally," he explained to Sky Sports in a separate interview last month.
Arteta puts it down to another quality which he regards as the 24-year-old's biggest strength. "His football intelligence," he added to Sky Sports, "how he reads the spaces, the timing of how he uses those spaces, how he moves in relation to his opponent."
Most important of all, of course, is that Havertz is doing all that while also scoring and assisting consistently, his confidence buoyed by the support of a manager who trusts him implicitly.
"For me, the most important thing is that players feel like we trust them, that we protect them, that we love them," added Arteta.
Those jubilant scenes of celebration at the Emirates on Tuesday showed he is feeling the love of the club's supporters too. More of the same against north London rivals Tottenham, live on Sky Sports on Sunday, would strengthen the connection further.