Fulham manager Martin Jol admitted John Arne Riise's leg injury is "serious" after his team had booked their place in the Europa League on Thursday night.
The Cottagers were beaten 1-0 by Dnipro but last week's 3-0 success in the first leg enabled their European adventure to continue.
However, left-back Riise left the action in the 22nd minute with a leg injury - and the summer signing could be absent for some time.
Jol said: "Riise has a serious problem with the leg, that's why I substituted him with Matthew Briggs."
On tonight's performance in the Ukraine, the Dutchman said: "We didn't want to lose, we wanted to defend our lead, to do our best.
"We are a great team and tonight we were very good in defence. It was great that we won at home.
"We could be better in attack and I wanted to see more from Andy Johnson tonight.
"We wanted to punish Dnipro for the goal when we went behind and I wanted us to take our chances to make it 1-1 at the end.
Dnipro won thanks to Evgeniy Shakhov's header, which came shortly after Riise hobbled off.