Simon Cowell Reportedly 'Healing Well' From Back Injury Amid Third Week of 'America's Got Talent' Absence

Simon Cowell's recovery has been "going well" 17 days after he broke his back falling off an electric bike. As America's Got Talent enters the third week of live quarterfinals, the series creator and judge has entered his third week of recovery after undergoing a six-hour surgery that required a number of spinal fusions and the insertion of a metal rod. A source told PEOPLE of the 60-year-old producer Tuesday, "Simon's healing has been going well. He's recovering at home."

His fellow judge, Howie Mandel, said on the Today show last week that Cowell "broke his back in four different places" and underwent a "six-hour surgery where parts of his back were fused" and a metal rod was inserted, but that just a day after the surgery, Cowell had "already been up on his feet and walking."

"I wouldn't count him out for the live shows yet," Mandel said of Cowell's possible return to the show before the end of the season. "You know, I would imagine, and if I know anything about Simon, it's that there may be a Simon sighting before the end of the season. As much as it's devastating, it's also good news that he is going to be fine and make a full recovery."

Meanwhile, Cowell has spoken out about his accident, breaking his silence on the crash after his Aug. 8 surgery. Taking to Twitter, Cowell joked, "Some good advice... If you buy an electric trail bike, read the manual before you ride it for the first time." He thanked "everyone for your kind messages" as well as "all the nurses and doctors. Some of the nicest people I have ever met."

Tuesday, Mandel and his fellow judges Heidi Klum and Sofia Vergara were without a guest judge as they and host Terry Crews kicked off the third round of live shows, in which 33 of the original 44 acts competed for a spot in the semifinals. Kelly Clarkson filled in for the first live show, while Kenan Thompson jumped in as the second guest judge of the quarterfinals. Next week is the fourth and final live show before the semifinal round. Season 15 comes to an end on Sept. 23 during the finale episode. Whether or not Cowell will appear at all in the rest of the season remains to be seen. America's Got Talent airs Tuesdays and Wednesdays at 8 p.m. ET on NBC. For more on your favorite America's Got Talent acts and judges from PopCulture, click here.