Even with Chelsea's first-choice striker Alvaro Morata out with a back injury, the Belgian international was not given the chance to impress head coach Antonio Conte – or any interested clubs watching.
Instead, Eden Hazard was given the nod up top in a false nine role, with Pedro and Willian in support.
Elsewhere, Willy Caballero gets the start in goal for Chelsea, as Thibaut Courtois will miss the match with an ankle injury.
For the Gunners, Henrikh Mkhitaryan will not be able to make his Arsenal debut, as the new arrival from Manchester United is cup-tied for the competition.
Nacho Monreal passed a late fitness test and will continue in defence for the Gunners while Jack Wilshere starts in midfield alongside Granit Xhaka and Mohamed Elneny.
Arsenal's 4-3-3 formation gives Mesut Ozil free roam in his No.10 role with Alex Iwobi and Alexandre Lacazette also playing in attack.
After a 0-0 draw in the first leg, whichever team emerges from Wednesday's second leg at Emirates Stadium will face Manchester City in the final.
Chelsea XI: Caballero; Azpilicueta, Christensen, Rudiger; Moses, Bakayoko, Kante, Alonso; Willian, Hazard, Pedro.
Chelsea subs: Eduardo, Cahill, David Luiz, Zappacosta, Drinkwater, Barkley, Batshuayi.
Arsenal XI: Ospina; Monreal, Mustafi, Koscielny, Bellerin; Wilshere, Ozil, Xhaka, Elneny; Lacazette, Iwobi
Arsenal subs: Macey, Chambers, Kolasinac, Maitland-Niles, Ramsey, Nelson, Nketiah