Former US Open champion will play Madrid, Munich in his first clay-court season in three years.
The 34-year-old is replaced by fellow Spaniard Marcel Granollers.
The Octagon-owned Biel/Bienne tournament will debut in April, 2017 at the Swiss National Tennis center.
Daniel Gimeno-Traver nearly took Pablo Cuevas out of his shoes with this sublime fake on Tuesday at Monte-Carlo
69-year-old Gail Falkenberg met her match in Taylor Townsend at the ITF Pelham event on Monday.
The 28-year-old is more obsessed with health food than he is with winning.
The 19-year-old will need to rest for four weeks.
