Sanchez, 28, was forced off against Everton last weekend but is likely to be passed fit for the Wembley clash against the Premier League champions.
Alex Oxlade-Chamberlain is also in contention after recovering from a hamstring strain, and could battle with Hector Bellerin for a starting berth.
But things aren’t looking as good in defence.
Skipper Laurent Koscielny is suspended after seeing a straight red for a reckless challenge on Enner Valencia.
Arsene Wenger’s problems are compounded by the absence of Gabriel, who will miss out with a knee injury.
Their wealth of injuries means Per Mertesacker could make his first start in almost 13 months, although he’s unsure if he's even fit enough to play.
Asked if he would be ready if selected, Mertesacker responded: "I cannot tell you.
"I haven't played this year. But I have done this for 15 years so I expect myself to be absolutely ready no matter what comes.
"That is my mindset, no matter what happens or what is facing me on Saturday, I am going to go for it. I owe this to this team and to this club.
“I want to make sure I will be ready and my mindset is '120 minutes plus penalties’.”
Late decisions will also be made on Kieran Gibbs, who has a thigh problem, and Shkodran Mustafi, who is struggling with illness.
Arsenal provisional squad: Cech, Ospina, Martinez, Oxlade-Chamberlain, Bellerin, Holding, Mustafi, Mertesacker, Monreal, Gibbs, Maitland-Niles, Coquelin, Xhaka, Ramsey, Ozil, Walcott, Iwobi, Sanchez, Perez, Welbeck, Giroud.
