Arsenal star taken aback by 'crazy' Premier League game against Burnley at Turf Moor
The 21-year-old capture from Anderlecht, who put pen to paper on a £15m deal in July, wasn't expecting the onslaught that greeted the Gunners at Turf Moor.
The Belgium international was handed a second half introduction by Mikel Arteta as he replaced Emile Smith Rowe with half-an-hour remaining.
His appearance came at a time when the visitors were desperately clinging on to their slender advantage, given to them by Norwegian midfielder Martin Odegaard before the break.
Sean Dyche's side had upped the ante after the interval in their search for an equaliser and penned Arsenal back.
But the visitors held firm and inflicted a 13th top flight game without a win for the Clarets on their own patch.
"The intensity here is crazy," he said. "When the other team counters you have to sprint. In Belgium I wasn't used to that, it's a big difference.
"It was a crazy game because they cross from everywhere. I was not used to it.
"People told me 'you're going to see this is the real Premier League, typical English way to play'. I was not expecting this kind of play."