Mark Pincus is stepping down as CEO of Zynga and will be replaced by the head of Microsoft's Xbox business, Don Mattrick, Zynga announced on Monday.
Pincus will stay on as Zynga's chairman and chief product officer, he said in a letter to employees posted on the Web. Mattrick, who was president of Microsoft's interactive entertainment business, starts at Zynga next week.
Microsoft confirmed Mattrick's departure but did not name a replacement. The managers who reported to Mattrick will now report directly to CEO Steve Ballmer, Ballmer said on Microsoft's website.
The factors behind the management change at the developer of "Farmville" and Words with Friends" weren't clear, though Zynga has struggled to maintain its early growth rate. In his letter, Pincus said he had always maintained that "if I could find someone who could do a better job as our CEO, I'd do all I could to recruit and bring that person in."
"I'm confident that Don is that leader," said Pincus, who has been CEO at Zynga for six years.
As head of interactive entertainment at Microsoft, Mattrick was a key player behind the development and marketing of the Xbox One, Xbox 360, Xbox Live, and Kinect gaming consoles and services, as well as PC and mobile products.
In Mattrick's time at Microsoft, Xbox Live members grew from 6 million to 48 million and Xbox 360 became the top-selling console in North America the past two years, Ballmer said.
Mattrick, who joined Microsoft in 2007, is also credited for his role in developing the "FIFA," "Harry Potter" and "The Sims" game franchises.
"Don is unique in the game business," Pincus said. "He can execute in multiple domains."
It's not known how the management changes might change Zynga's products in the months and years ahead. Its offerings have historically been linked to Facebook's platform but the games maker has struggled in recent years. Last month it said it would be laying off 18 percent of its workforce to reduce costs.
Besides "Farmville," Zynga's best known games include "County Fair" and "Zynga Poker." Though its "Farmville" franchise had been "perform[ing] well, other games are underperforming," the company said last month in its layoff announcement.
Closures of "The Ville," "Empires & Allies," "Dream Zoo" and "Zynga City" on Tencent were announced in April.
In an effort to grow its user base, in March the company made changes to let users create their own accounts on the Zynga site, instead of requiring them to log in through Facebook.
Zynga was founded in 2007 and went public in 2011. Following the news, its shares were up more than 10 percent in after-hours trading.