Arsenal could be without THREE key stars for their Champions League showdown with Shakhtar Donetsk . The Gunners host the Ukrainian side at the Emirates Stadium on Tuesday for their latest group game. But Mikel Arteta has a host of issues to consider ahead of the clash. Arsenal captain Martin Odegaard remains sidelined with the serious knee injury that he sustained last month. Bukayo Saka is also a doubt - he pulled out of international duty and then missed the weekend defeat to Bournemouth.