Arsenal manager Arsene Wenger has confirmed striker Danny Welbeck injured his groin in the draw at Chelsea.
The England international was named in the Gunners' starting line-up in the 0-0 draw at Stamford Bridge on Sunday but was substituted with the injury after 73 minutes.
Olivier Giroud replaced the 26-year-old Welbeck for the final 17 minutes of the goalless stalemate.
Welbeck will have scans on Monday or Tuesday with the extent of the injury expected to be known later in the week.
Wenger confirmed the injury on Sunday evening and said he did not know how long he would be without the forward.
"He has a groin problem," Wenger said. "I don't know how severe it is but it looks like a 'good' groin problem, not an easy one."
Welbeck has scored 20 goals in 52 starts for Arsenal since a £16m transfer from Manchester United in September 2014.
He made only 20 appearances for the club last season due to injury problems.