As one-time TV watchers become streaming-video fanatics, advertisers are grappling with an uncertain future. But they will have a familiar face to guide them on at least part of the journey.

Jo Ann Ross, one of the advertising industry’s best-known executives, will lead ad-sales efforts at ViacomCBS, the company that is expected to rise from the merger of CBS and Viacom sometime in early December. She will serve as President and Chief Advertising Revenue Officer, ViacomCBS Domestic Advertising Sales, and report jointly to Bob Bakish, who will be the CEO of the new company, and Joe Ianniello, who will be chief executive of its CBS operations.

“This is really the first step in building a unified sales team,” Ross said in an interview with Variety on Wednesday. “We will be organized. We will be strategic. And we will be speaking with one voice.”

Ross, who is the first female executive to lead a broadcast-network ad-sales team, has been at the helm of CBS’ outreach to Madison Avenue since 2002, will guide the new company’s efforts to sell advertisers on everything from Stephen Colbert’s “Late Show” to Trevor Noah’s “Daily Show.” She will have to keep pharmaceutical marketers interested in “CBS Evening News” under a new anchor, Norah O’Donnell, and spur toymakers to keep supporting Nickelodeon. CBS secured nearly $6.2 billion in advertising revenue in 2018, the bulk of it generated by efforts by executives working for Ross. Viacom notched approximately $1.15 billion in revenue in its fourth fiscal quarter.

Ross’ ascension signals the importance of having a trusted operator when it comes to maintaining the flow of millions of dollars in advertising, even as blue-chip marketers like Coca-Cola and Procter & Gamble are investing in new ways of reaching consumers through video, and upstart marketers like Wayfair and Casper are moving into TV with greater expectations of generating sales. Her credibility, media buyers say, comes from the value of her word  in an era when new entertainment giants like Comcast, AT&T and Walt Disney have placed more emphasis on getting sponsors to buy bigger and bigger packages of inventory.

Some advertisers still prefer a handshake they can rely upon over an algorithm that can place commercials seamlessly across multiple content windows. “There’s a tone of trust there,” said one media-buying executive about Ross’ standing with advertisers and agencies. Many traditional media operators like to compare themselves to their digital rivals, and promise similar capabilities, but Ross “doesn’t pretend she’s the next Facebook,” this buyer says. “I think you’re going to be hard-pressed to find someone to say, ‘I got screwed by a Jo Ann deal.'”

Ross will work with John Halley, COO, Advertising Revenue, and EVP, Advanced Marketing Solutions, at the new company, who will report to her. Sean Moran, a 24-year veteran of Viacom ad-sales, who rose from leading ad-sales efforts at MTV and VH1 to supervising Viacom’s entire efforts in mid-2016, will leave the company.

To be sure, Ross will face obstacles. The new company will have to sell broadcast, cable and digital together, all the while using CBS’ biggest properties to snare the biggest amount of interest and highest prices, and drive new interest in Viacom’s fare, even as younger viewers find other ways to access clips of “South Park” or an MTV favorite. The two sides have not worked in such a way in the past. Even when CBS and Viacom were part of the same corporate entity before being separated in 2006, the two sides largely went to market separately.

A new sales team will have to assign areas of expertise to various members. CBS is largely accustomed to dangling big-audience TV shows like “NCIS” and “60 Minutes” in front of clients, not programming tailored for narrower viewer sets. Meanwhile, Viacom has struggled in years past to maintain the integrity of its linear video advertising in the face of ratings declines. The company this past summer posted its first quarter of positive ad-sales growth after a five-year span.

Even so, the combined CBS and Viacom will control 20% of national TV advertising, according to Standard Media Index, a tracker of ad spending, making Ross the gatekeeper to a sizable chunk of the commercial inventory most desired by Madison Avenue. The merger stands to enhance much of that commercial time. Under Moran, Viacom moved into working more directly with social-media influencers and YouTube, and gained valuable expertise in streaming-video thanks to Viacom’s recent acquisition of video hub Pluto. Media buyers say Viacom has also been a leader in the growing practice of using data to help advertisers place commercials more precisely to reach smaller  niches of the most likely customers. Moran “had the foresight to quickly reposition our go-to-market strategy and evolve our business to engage marketers across more touch points than ever before,” said Bakish, in a memo to employees sent Wednesday.

“Incorporating CBS assets into these capabilities makes them more powerful,” Halley told Variety in an interview.

“We are really looking forward to having deeper, more meaningful conversations with clients that we haven’t been able to have before,” says Ross. “We are going to engage customers in every way we can, using all of the advanced marketing capabilities. We can provide some solutions for questions that clients are asking.”

Several media-buying executives said they expect the new company to retool the presentation it makes next year to advertisers as part of the industry’s annual “upfront” advertising market. CBS has long relied on a showy day at New York’s Carnegie Hall to get Madison Avenue excited about buying CBS primetime properties like “Young Sheldon” or the various “NCIS” dramas. But a 2020 event, these buyers suggested, would make use of the Viacom cable networks and other properties. Ross declined to comment on upfront plans, noting that the announcement of her new duties signals just the start of a larger process of examining how to work with advertisers in weeks to come.

Given her long tenure at CBS and in the industry, no one would have been surprised if Ross had decided to step down. But the executive says she is looking forward to the challenges and conversations ahead – and doesn’t want to just put in a year or so in her new role before moving on to something else. “I am here for the long game,” she says.