Troussard tapped home Mikel Arteta’s side in the 29th minute and Saka underlined Arsenal’s superiority with a superb effort midway through the second half.
Europa League champions Sevilla were abysmal and managed just one shot on target with the last kick of the game, as their hopes of progressing to the last 16 faded.
Lens and PSV have five points and winless Sevilla are bottom with two points.
After Arsenal’s controversial Premier League defeat to Newcastle United at the weekend, which sparked an emotional Arteta outburst, a nightly routine was needed and Sevilla were loyal opponents.
“We knew we had to get the three points and we did,” Arsenal midfielder Declan Rice said. “After this upset [League] Cup last week and then at the weekend, the manager made it clear before the game that a club like this cannot lose three games in a row.”
The Andalusian club has endured a disappointing start to the season and the recruitment of exes Uruguay National Diego Alonso barely revived their fortunes a month ago.
They have won just one of their first five games since replacing Jose Luis Mendiliber — Copa Del Rey — and they didn’t look like pulling off a surprise victory in north London.
The hosts then took the lead JorginhoThe captain, replacing the injured Martin Odegaard for the night, released Saka on the right and he slid a pass for Trossard to score his second Champions League goal of the campaign.
Havertz twice went close to goal after the break, a goalbound shot deflected wide and another effort agonizingly wide of the far post.
Saka finally gave Arsenal some breathing space with a superb, on-the-run effort Gabriel MartinelliGoes to the right of it and then turns inside to fire a left-footed shot past the visiting keeper Marko Dimitrovic.
Arsenal keeper David Raya Could have had the night off, such was his lack of involvement in the game, with his only save coming in the sixth minute of stoppage time on Mariano Diaz.