Mikel Arteta fears Bukayo Saka's hamstring injury "is significant" after the winger pulled up in the second half of Arsenal's 5-0 win over Leeds.
The England international scored Arsenal's second goal in their home opener but went down without contact before the hour mark and was immediately replaced by Leandro Trossard.
It was a bittersweet day in general for Arteta and Arsenal, as the club announced the signing of Eberechi Eze from Crystal Palace, before Viktor Gyökeres marked his first two Premier League goals.