The 23-year-old came off the bench in the Europa League against FC Zurich but then had to be withdrawn in the final few minutes with an apparent muscular problem in his leg.
It is currently unclear how long the issue might keep Tomiyasu out for, but given his history of injuries, it would be a surprise to see Mikel Arteta take any chances this weekend.
Thankfully for the Gunners boss, Oleksandr Zinchenko has now fully recovered from a calf problem and was on the bench on Thursday to watch Kieran Tierney score the goal that sent Arsenal through to the last 16 of the Europa League.
Tierney's man-of-the-match performance has given Arteta the best kind of selection dilemma, but as long as Zinchenko is fit enough, the Ukrainian should be given the nod at left-back.
Matt Turner missed out on Thursday with a groin problem, but Aaron Ramsdale was always going to start in the backline with Ben White, Gabriel Magalhaes and William Saliba, the latter of whom will replace Rob Holding.
Emile Smith Rowe remains in the medical bay, but Bukayo Saka quickly shook off the injury scare that he sustained against Nottingham Forest and will link up with Gabriel Martinelli and Gabriel Jesus up front.
Arsenal possible starting lineup: Ramsdale; White, Saliba, Gabriel, Zinchenko; Xhaka, Partey; Saka, Odegaard, Martinelli, JesusNo Data Analysis info