However, Wenger says Lacazette took part in a full session outside today at London Colney and will be available again after the upcoming global break.
Arsenal's season now hinges on success in the Europa League as they are languishing in sixth place in the Premier League, which means winning the cup competition is the only realistic way of qualifying for the Champions League next season.
In spite of many big-name managers been linked with the Emirates job, Paul Merson feels Brendan Rodgers should be the man to replace Arsene Wenger.
"It's important we treat it as 0-0 and go out there for the win".
It means Alexandre Lacazette is the only player now on the sidelines through injury as the French global is still working his way back to fitness after undergoing knee surgery last month.
Recognising that internal strife will dent Arsenal's bid to get back on track in the closing weeks of the season, Mkhitaryan called on supporters to show their true colours. Our objective is there in front of us, but we've got to take things game by game. They still, however, remain a long way from the dominant team they were over a decade ago.
A 2-0 win in the last-16 first leg over AC Milan at the San Siro holds them in good stead for the return fixture on Thursday night.
"To do what they've done, people can say it's Scottish football and Celtic are head and shoulders above, but every team they played on that run treated it like a cup final, which is hard sometimes". They've turned a corner as well with their new manager.
Vieira, who has been the head coach of New York City FC since 2016, says he "adores" Wenger, whose future is the subject of increasing speculation.
"You always pick the team you think has the best chance to win the next game".