Andy Murray's withdrawal from the US Open draw on Saturday strikes Rafael Nadal as strange.

Murray has been bothered by a hip issue in recent months.

Watch: Nadal Aiming to Lift Level

The world No. 1 said the Scot's decision to pull out a day after the draw was made was "difficult to understand."

"I always thought that he gonna be playing if he was here practicing, no?" Nadal said. "Was a little bit strange that he retired just the morning after the draw was made. Was something that is a little bit strange and difficult to understand, but the worst thing is, yeah, he is not healthy and I wish him a very fast recovery.

"Injuries are bad for everybody. I know better than all of them. So I wish him fast and good recovery. That's the most important thing."

The 15-time Grand Slam champion said he was surprised Murray didn't give himself another day or two before pulling out.

"Normally when you retire on... was Saturday morning? And the draw was made Friday? Normally you want to keep practicing, keep trying until the last moment," Nadal said."You don't retire Saturday morning. You retire Monday morning or Sunday afternoon, not Saturday morning.

"If not, you can do it before the draw. That's why I say it's strange. But of course he has his reason, and for sure the negative the only news and the negative news was that he will not be playing here."

Photo credit: Mutua Madrid Open