Rafael Nadal has described the timing of Andy Murray's withdrawal from the US Open as "strange".
Nadal, who began his campaign in New York with a straight-sets victory over Dusan Lajovic on Tuesday, also described Murray's decision as "difficult to understand".
The world No 2 appeared set to feature in New York having practised at Flushing Meadows for a week only to decide after a final hit on Saturday that his hip was too sore to compete.
If Murray had pulled out prior to Friday's draw, Roger Federer would have moved up to second seed and he and Nadal would not have been in the same half of the draw leaving the door open for a final between the illustrious pair.
"I always thought that he was going to be playing if he was here practising," said Nadal.
"It was a little bit strange that he retired just the morning after the draw was made. It was something that is a little bit strange and difficult to understand.
"Normally you want to keep practising, keep trying until the last moment. You don't retire Saturday morning. You retire Monday morning or Sunday afternoon. 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 only news, and the negative news, was that he will not be playing here.
"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."
Murray's timing wasn't the only thing occupying Nadal following his first-round win as he admitted it had been too loud under the closed roof of the Arthur Ashe stadium, which became a giant echo chamber for the boisterous 24,000-strong crowd as rain lashed down outside.
"Being honest, it (the noise) is a little bit too much," said the 31-year-old. "The energy and support of the crowd is massive. I enjoy it and I have unforgettable memories from this tournament and this court because the energy is different from in other places.
"But at the same time, under the roof, it's too much noise. I was not able to hear the ball when hitting. I understand it's a show, but under the roof we need to be a little bit more strict about the noise. All the noise stays inside, and this is difficult."
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