The World No. 13 American won his first clay-court match of the season on Thursday, defeating Alejandro Tabilo 6-1, 6-4
Sonego won his first Challenger title on October 17, 2017, when he defeated Tim Putz at the 2017 Sparkassen ATP Challenger.
Despite not having won an ATP title in his career, he has finished second in four singles finals and one doubles final.
The injury blow will affect his build-up up to the next Grand Slam of the year - the French Open. The Roland Garros takes place from May 22nd to June 5th.
The Spaniard said that he felt a lot of pain during the match and had a hard time breathing and that the pain made him feel dizzy.
The 24-year-old was overcome with emotion at the end of the game and it was pretty evident that he viewed the victory as the biggest of his career so far.
The three-time BNP Paribas Open champion beat his fellow Spaniard 6-4, 4-6, 6-3 to reach his fifth final in the California desert.
On Monday, the home favourite will face Rafael Nadal of Spain in arguably the most important match of his career.
Early in the decider, the 20th seed got his first break of the match on his eighth chance, then took the lead and cruised to victory.
Amazingly, he won his first-ever match on tour - and that win came against an established name in Pablo Carreno Busta.