Arsenal travelled to the Midlands to face a Villa side who beat them twice in the Premier League last season -- defeats that ultimately cost them the title -- and had to weather plenty of pressure from an impressive home side.
At a crucial juncture in the match, however, Trossard took his chance, sweeping home with his first touch after coming as a substitute to set Arsenal on their way to a 2-0 victory.
Six of Trossard's 14 Premier League goals for Arsenal have been as a substitute, the highest share of any player to score 10 or more goals for the club in the competition.
With Manchester City starting with two wins from two in pursuit of a fifth successive Premier League crown, impact players off the bench like Trossard will be vital for Arsenal.
"First of all when you don't get picked there are certain ways to react," coach Mikel Arteta told reporters. "Leo (Trossard) is upset, but he's upset he could not show on the pitch how good he is, not upset because he wasn't playing.
"That's a huge quality. When you put him in the starting XI he does exactly the same thing. That's a big message and a big example for the rest of the team and myself."
On another day Villa could have made the most of their opportunities and inflicted more damage of Arsenal’s title chances, as they did last season.
The resilience Arsenal showed at Villa Park, however, stands them in good stead to keep pace with City.
"When we made the changes, the impact they had was tremendous," Arteta added. "When the team starts to be equipped that way and starts to be able to navigate through different contexts in the match, it becomes a team that can win in every place. Today we showed that.
"When we had to rely on certain individuals we did, and that's not a bad thing."