At what point does Mikel Merino come to be seen as a striker who sometimes plays in midfield, rather than a midfielder who fills in up front? His match-winning display against Brentford was just the latest example of him playing the role as if a natural.
The 29-year-old has either scored or assisted in five out of six starts up front for Arsenal since the Viktor Gyokeres injury that saw him drafted back into the position. Against Brentford, he did both, heading in the opener, then feeding Bukayo Saka for the second.
"He was immense again today," said a beaming Mikel Arteta, before lauding the instinctive centre-forward play that led to his opening goal. "The way he scored the goal, super smart. His timing, the way he wins the position and execution."
His total of eight headed goals since the start of last season is the most by any Premier League player in all competitions.
All this from a central midfielder who had, until Kai Havertz's hamstring injury last season, never previously played the role.
There is learning on the job and then there is this. Merino has mastered the position and has the numbers to prove it.
Since the turn of the year, he has scored an extraordinary total of 21 goals for club and country, his transformation into a goal-getting centre-forward benefitting the Spanish national side as well as Arsenal. Merino has emerged as a crucial spearhead for both sides.
Arsenal have Gyokeres and Gabriel Jesus available again, with Kai Havertz not far behind them. But they will likely all struggle to dislodge Merino, whose value to the side is not limited to his goals. "He makes the team much better," as Arteta put it afterwards.
Since his move up front at the start of last month, Arsenal have scored 15 goals in six games, their average jumping from 2.1 per game to 2.5 during a run which has included their two best attacking performances of the season, against Spurs and Bayern Munich. Merino has either scored or set up nearly half of the total.
Of course, he is different to Gyokeres, for example, in that he does not play the role as a conventional No 9.
When he is not sniffing out chances in the box, he is dropping into midfield, interchanging positions with team-mates, creating space to run into and generally confusing opposition defenders.
In his four Premier League starts up front this season, Merino has averaged half as many touches in the opposition box as Gyokeres per 90 minutes but nearly twice as many overall touches and passes, highlighting the extent to which he knits things together.
Arteta was eager to highlight the work he gets through out of possession too. Merino has shouldered a heavy workload lately, starting eight consecutive games in a month for club and country, but you would not have known it to watch him on Wednesday.
"I remember an action, he passed the ball to Martin [Odegaard] in behind and Martin doesn't chase it. Merino makes 40 metres to chase it to the corner flag," said Arteta.
"He goes back, wins the ball back. He is everywhere. He's got that really good momentum at the moment."
Merino made four tackles in the game. Premier League tracking data showed he ran more than 12 kilometres, his total putting him behind only Odegaard. No player made more than his 368 intensive runs.
The tireless work-rate was not unusual. As well as providing more goals and assists than any other Arsenal player across the last four Premier League games, Merino has made a total of 10 tackles which puts him second only to left-back Riccardo Calafiori.
His all-round contribution, off the ball as well as on it, sets him apart and he has another vital attribute too.
"I said it earlier in a press conference, it's his curiosity, it's his will to learn and probably his will to help the team," added Arteta.
"He knew that we had a major problem from the beginning of the season. We lost Victor, Kai was out and Gabriel Jesus was out. So we needed a solution and he did it last year really, really well.
"I think this season he's probably taken it to another step because he's able to do even more things.
"I think the team is really grateful and he's enjoying it."
Arteta feels his success in the role is a lesson for others. It has offered learnings to him too. Having worried about having too many strikers in the summer, Merino has saved the Arsenal boss from a situation where it appeared he didn't have enough.
"I took that lesson because the whole summer I was thinking, if we bring a nine, what's going to happen with Gabriel Jesus and Kai Havertz? I had a lot of madness because I like them so much as well.
"What are we going to do? How are we going to handle it? And so far we haven't had a problem because they've been injured.
"So, leave the present, leave the moment and deal with the situation when it comes. That's it."
And that is what Merino has done too. The stand-in striker might just be Arsenal's best option in the position now. Gyokeres, Jesus and Havertz have a fight on their hands to get back into the team.
