I’d lean toward Gabriel Martinelli as the starting left-winger.
Here’s why:
Directness & Pace – Martinelli is one of the few Arsenal players who can consistently stretch defenses, run in behind, and beat his man 1v1.
Work Rate He relentlessly tracks back to support the left-back, which is crucial given Arsenal’s high-press and overlapping full-back system.
Big-Game Mentality He has a habit of turning up in important matches (Liverpool, Man City, Chelsea last season).
That said, Leandro Trossard is also a strong case if Arsenal want a more technical, possession-based approach his finishing and link-up play can unlock stubborn low blocks.
So, for me:
Against high defensive lines: Martinelli.
Against deep-lying, compact teams: Trossard.