Some of 21st Century Fox‘s best-known ad-sales executives will leave the company when it closes a large sale of its assets to Walt Disney and streamlines itself into a company known currently as “New Fox” in 2019.

Bruce Lefkowitz, executive vice president of ad sales at Fox; Mike Denby, a senior vice president of ad sales; and Jake Piasecki, another senior vice president, will no longer be part of Fox when it sells the bulk of its holdings to Disney next year, according to four people with knowledge of the matter. The executives could potentially be hired by Disney, two of these executives said.

Fox declined to make executives available for comment.

Their departure represents the first step in a reshaping of the unit under a new chief. Marianne Gambelli (pictured, above), a veteran who once led ad sales at NBC, has been named president of ad sales for the “new” Fox, and will oversee efforts for units like Fox Sports, Fox News Channel, Fox Business Network and Fox Broadcasting that will remain after the $71.3 billion deal closes next year.

Fox will be the latest media company to rejigger its ad-sales structure at a time when the rise of streaming, on-demand video is reshaping the industry. Disney recently combined its ESPN and ABC ad-sales units under a single executive, while NBCUniversal has reordered the executive structure of its ad-sales operations.

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Gambelli is respected by many media-buying agencies. She arrived at Fox in 2017 to lead ad sales at Fox News as it grappled with allegations of harassment made against former chief Roger Ailes and one of its leading hosts, Bill O’Reilly. Both have denied charges levied at them; Ailes passed away in May of 2017. She had been chief investment officer at Horizon Media, a large media buyer, and before that was president of sales and marketing at NBC, overseeing efforts for the NBC broadcast network and NBC Sports.

There is some speculation among ad sales executives that Gambelli might try to work with some of the same senior leaders who reported to her at NBC. Seth Winter, a colorful ad-sales executive who led NBC’s efforts behind the Super Bowl and the Olympics, among other sports properties, is in talks to join Fox in a similar capacity, according to three people familiar with the situation. Winter in October of 2016 left his job as executive vice president of ad sales for NBC Sports and became a consultant to the company, a role he was expected to carry out through 2018.

Fox has placed new emphasis on the power of live sports to attract big audiences. In recent months, the company signed a five-year deal to air “Thursday Night Football,” won rights for the WWE’s “Smackdown Live” and even snapped up rights for  Saturday bowling. Last week, Fox expanded its rights deal with the New York Racing Association.

Over the years, Winter has developed a reputation for making big bets on the power of sports properties. He has been known to start his drive to win ad money months ahead of big events and has never been afraid to ask for top dollar. Winter began his tenure at NBC in 2000, when he joined as vice president of sales at MSNBC. He has also been a general manager of a Orlando TV station.