FOOSH. That’s not the sound of a Jannik Sinner tennis serve flying by you. Instead, that’s the type of injury that Italy’s Sinner suffered during his U.S. Open semifinal victory over England’s Jack Draper. FOOSH is a medical acronym that stands for “fall on an outstretched hand” because who has the time to say all those words. The big question is how much will Sinner’s left wrist be on the fritz when he plays against American Taylor Fritz in the men’s singles finals on Sunday?

Sinner’s FOOSH injury happened during a point in the second set of his 7-5, 7-6 (3), 6-2 win. The 23-year-old Sinner was retreating to get a ball when fell backwards on to his left outstretched hand. He won the point but then subsequently received treatment to his left wrist including a massage from trainers. Sinner, who is the top seed in this year’s U.S. Open men’s singles draw, then was seen icing his left wrist after the match.

FOOSH injuries are quite common because when you fall you tend to extend your arm and hand towards the ground to brace yourself. The impact of the hand with the hard surface can then send forces through your fingers, hand, wrist, forearm, elbow, upper arm and shoulder. These forces can then cause damage to any of those body parts.

FOOSH injuries can vary in severity from bruising to wounds to sprains to bone fractures to joint dislocations. Therefore, one of the first things to do after a FOOSH is to thoroughly check your entire upper extremity and each of the bones and joints to rule out any fractures or dislocations. Fractures and dislocations require immediate medical attention to determine whether a brace or surgery is needed.

It doesn’t look like Sinner suffered any fractures or dislocations. But that doesn’t mean the FOOSH injury won’t affect his play on Sunday when he takes on Fritz. A soft tissue injury, tendon strain or ligament sprain could still affect the strength and mobility of his left wrist.

Now, you may point out that Sinner is right-handed and an injury to his dominant wrist would have been much worse. That would be true. But his left hand and wrist will still play roles in all of his strokes.

Clearly, his left hand is important in his two-handed backhand because that’s why it is called two-handed. His left wrist will be a significant part of the swing and thus could affect his power and placement on that side.

And even though his forehand is one-handed, his non-dominant left hand will help hold the racket in the ready position while waiting for the ball to return to his side of the court, track the ball before and during the forehand swing and follow-through after his racket strikes the ball.

Then there’s his serve. His left hand will be tossing the ball up to initiate the serve. It will also be part of the follow-through after his racket hits the ball and thus can affect where the ball goes.

Ultimately, how much the FOOSH injury affects Sinner’s play will depend on how stiff and painful his wrist is and whether it’s mobility and range of motion are affected. Therefore, one of the things he will probably do is try to reduce the swelling by RICE—meaning rest, ice, constriction and elevation and not the stuff that’s under sushi—and anti-inflammatory medications. He may get some physical therapy to keep the wrist supple as well.

Without knowing the extent of Sinner’s injury and being able to directly examine his wrist, you can’t really tell how much his FOOSH injury will play a role in the U.S. Open men’s single finale. You could say it is still an open question.