The 32-year-old Spaniard's right knee flared up in the second set of his 7-6 (2), 7-6 (2) victory over Karen Khachanov on Friday in the quarterfinals.
Federer now has a chance to claim his 101st career ATP singles title on Sunday.
Assuming he does take to the court, Nadal will face his great rival for a 39th time, looking to improve his winning record to 24-15.
Nadal isn't sure how severe the injury but has no doubt that he'll be ready for the Monte-Carlo Masters, beginning April 13. "It has been a great week for me even though it didn't work out today", he told the crowd in the presentation ceremony. Then, of course, there are going to be many games where I will have zero chance on his serve.
In the end, it was a much cleaner performance by Thiem who reaches his first hard-court Masters 1000 final.
Momentum swung in Andreescu's direction when she broke back to level the set at 3-3 and held serve to love in the next game.
"I had to get used to Roger's game".
Thiem collapsed onto his back in delight as he secured his first title at a Masters 1000 event.
Andreescu would love to follow in the footsteps of world number one Naomi Osaka of Japan, who won the tournament a year ago before claiming the USA and Australian Open titles. By the third game of the final set - the 25-year-old Austrian had just one forehand unforced error to 20 for Raonic.
Nadal choked up discussing his withdrawal last fall, and he appeared near tears Saturday. Sometimes I feel sad because I'm in a disadvantage to all my opponents.
"For me it's not about only today".
Federer, who also lost in the final of the tournament previous year, raced to an early lead, winning the first three games before wrapping up the first set in the Southern California desert. The hours logged on the practise court were evident and Thiem delivered a high-quality brand of attacking tennis that gave no indication of his 3-4 record to start the season.
"My goal is to play on all the surfaces, " he said. Federer is priced at [1.30] on the Exchange, very similar to my model, which priced the Swiss man at [1.35] to lift the trophy tonight, probably at around midnight United Kingdom time - the match is scheduled to start not before 22:30 United Kingdom time, after the conclusion of the women's final.
- Space-Marooned Iron Man Lands Back at Earth in 'Avengers: Endgame' Trailer
- Tesla unveils a new SUV, the Model Y
- Cyclone Idai Leaves Scores Dead in Zimbabwe, Mozambique
- DUP issues its final demands to get May's deal over line
- Cavs Players Clown on Odell Beckham Jr.’s Move to Cleveland Browns
- Australian Man Appears In Court On Murder Charge After Christchurch Attack
- Mumbai Bridge Collapse | Here is What Exactly Happened
- One Charged With Murder in Wake of Christchurch Shootings
- Bianca Andreescu continues fairytale run to reach Indian Wells final
- West Point Faces Flood And High Wind Watches This Week