World No. 2 and 2012 champion Andy Murray has pulled out of the US Open less than 48 hours before the tournament is set to begin.

Murray, who lost his spot to Rafael Nadal atop the rankings on Monday, was scheduled to play American Tennys Sandgren on Day 1 of the US Open on Monday.

“Obviously had the issue with the hip … since my match with Stan in Paris,” Murray said at a press conference Saturday afternoon in New York. “Did pretty much everything that I could to get myself ready here and took a number of weeks off after Wimbledon. I obviously spoke to a lot of hip specialists. Tried obviously resting, rehabbing, to try and get myself ready here.”

Under Grand Slam rules, if a top-four seed withdraws prior to the release of the order of play for the first day of the main draw, the fifth seed is moved into the open position; the fifth position shall be filled by the 17th seed; and the 17th position shall be filled by the next-highest ranked player eligible to be seeded.

Related: How Murray's withdawal impacts the men's draw

This means that No. 5 seed Marin Cilic moves to Murray’s position and will play Tennys Sandgren. Sam Querrey moves to Cilic’s position and will play Gilles Simon.  Philipp Kohlschreiber replaces Querrey and will play Tim Smyczek. Lucky loser Lukas Lacko has now gained entry to the men’s singles main draw.

Murray said he would not have been hurting himself more by trying to play, but that he is not at 100 percent and isn’t able to move the way he is able to when healthy.

“It was more a question of whether it would settle down in time,” Murray said. “Obviously I kind of ran out of time.

“You know, was actually practicing OK the last few days, but it's too sore for me to win the tournament and ultimately that's what I was here to try and do. Unfortunately, I won't be playing here this year. I want to be back on court as soon as I can. If it means that I can play before the end of the year, then that's what I would love to do. I miss competing, and I'll try to get myself back on court as soon as I can.”

Related: Andy Murray press conference transcript

It marks the first time Murray, who turned 30 this spring, will miss the final major of the year. He has played each of the past 12 US Opens since turning pro in 2005. The last Grand Slam he missed was the 2013 French Open when he had a back injury.

Murray's absence opens up the entire bottom half of the draw, and the fourth quarter in particular. The biggest beneficiary appears to be French No. 8 seed Jo-Wilfried Tsonga, who would have met Murray in the quarterfinals, and No. 4 seed Alexander Zverev of Germany, who was set to meet Murray in a blockbuster semifinal.