Del Potro was able to beat Serbian Viktor Troicki 4-6 6-1 6-4 in the last eight, but sustained a wrist injury when he fell on court.
He has had previous problems with his wrist, undergoing three operations, and the latest injury is a real worry ahead of the Federer tie this weekend.
The 29-year-old says he will consult his doctor, with the injury on his mind.
He said: "I felt something wrong in that moment but I continued to play with slices to try to finish the match, but now it's time to see what the MRI (scan) and also what the doctor says.
"I'm a little worried, but I know to deal with all of these things as I have been through them in the past, but I will see what the doctor says now and then we will take a decision for tomorrow.
"Of course I would like to play, I would like to be 100 per cent, but we will see in a moment what's happened."