Winston Salem - Two-time defending champion John Isner and top-seeded Czech Tomas Berdych on Monday withdrew from the ATP Winston Salem Open, both citing injury.
"I've had so much success playing in front of great crowds as well as my friends and family," said Cincinnati finalist Isner 24 hours after losing to Rafael Nadal in Ohio.
"This was a really tough decision but with injuries (knee) taking me out of the Australian Open and Wimbledon, I need to fully heal prior to the US Open."
Isner has won the only two editions ever played in Winston Salem, an event which was moved to the southern city in 2011.
The American pulled out after speaking to doctors about his condition.
Lucky losers in the qualifying round will replace the seeded pair in the tournament draw.