The Belgian winger - a new £26million signing from Brighton - comes in for his full Gunners debut in a mammoth fourth-round tie at the Etihad after impressing off the bench in a last-gasp 3-2 win over Manchester United last weekend.
Jakub Kiwior joined Arsenal from Spezia on Monday afternoon, for an initial fee of £17.5m, and he is on the bench this evening.
Gunners boss Mikel Arteta is without Emile Smith Rowe at City tonight, along with fellow injury absentees Gabriel Jesus, Mohamed Elneny and Reiss Nelson.
“I see a player [in Trossard] that is willing to make things happen and who is really composed, especially in the final third,” the Spaniard said at his pre-match press conference.
“It’s something we needed in the team and straight away he had a beautiful impact in the team to help us to win it.”
Arteta faced a dilemma as to who he starts in goal, with Matt Turner usually given the nod over Aaron Ramsdale in cup games. That is the case again tonight.
Arsenal starting XI: Turner; Tomiyasu, Holding, Gabriel, Tierney; Vieira, Partey, Xhaka; Saka, Nketiah, Trossard
Subs: Kiwior, Ramsdale, White, Zinchenko, Saliba, Lokonga, Odegaard, Marquinhos, Martinelli
Friday 8.00pm GMT, ITV
Venue: Etihad Stadium
Referee: Paul Tierney
Injured: Elneny (knee), Jesus (knee), Nelson (hamstring), Smith Rowe (thigh)