Rafael Nadal said on Tuesday he would be out of action for between four and six weeks with a stress fracture of the rib.
"This is not good news and I did not expect this," tweeted Nadal, who will miss the start of the claycourt season.
The 35-year-old Spaniard will be ruled out of the Monte Carlo and Barcelona tournaments although he could potentially return for the Madrid Masters on May 1-8.
His main focus will be on being fit for the French Open which begins on May 22. Nadal has won the title at Roland Garros 13 times.
The injury occurred on Saturday during the semifinal of the Indian Wells Masters.
Nadal went on to lose to American Taylor Fritz in the Indian Wells final on Sunday, ending his perfect 20-0 run to start 2022 which had included winning the Australian Open title.
He required treatment twice during the defeat to Fritz.
Nadal tweeted that he had undergone medical checks on his return to Spain.
"As it turns out, I have a stress fracture in one of my ribs and will be out for 4 to 6 weeks," Nadal said.
Nadal beat Daniil Medvedev in an epic final in Melbourne after Novak Djokovic was deported from Australia over his Covid vaccination status.
That victory gave him a men's record 21st Grand Slam title, moving him out of a tie with Djokovic and Roger Federer.