Injured Del Potro fears Shanghai Masters heartbreak

If the Argentine does miss out it will be just the latest injury heartbreak for the 29-year-old, who has had four previous operations on his wrists.

The 2009 US Open champion clambered off the court floor to knock out Serbia's Troicki 4-6, 6-1, 6-4 in the quarter-final on Friday.

The 16th seed is scheduled to meet Swiss great Roger Federer for a place in the final.

But Del Potro, who has suffered years of wrist injuries that have threatened his career, took a nasty tumble at 2-2 in the deciding set and most of the weight of his body ended up on his outstretched left hand.

Immediately after battling to victory he was off to see a doctor to have the injury looked at.

"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," Del Potro said.

"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 percent, but we will see in a moment what's happened."

Del Potro's foot appeared to get stuck on the floor and he crumpled down, landing on his left hand and bending it painfully backwards.

He has had three operations on his left wrist.

He needed several minutes of medical attention and sat on a chair at the back of the court, wincing in obvious distress.

Incredibly, he broke the serve of the unseeded Troicki on his immediate return to action.

"I'm glad to reach the semi-finals in a Masters tournament but now always health is the first thing always in my life," he said.

"I've been dealing with all of my injuries in the past and it's time to take care of my body and see what the MRI or doctor says.

"If nothing dangerous happened I will be here to play tomorrow and doing my best."