Fox Sports announced this week that Wieden + Kennedy would be its first ad agency of record. The agency's New York office will run the business, with the relationship beginning immediately.

This news marked the end of an era since W+K had been working with ESPN for 25 years, creating memorable campaigns for several properties including, most prominently, SportsCenter. In fact, Wieden has been working with ESPN longer than Fox Sports has been on the air; the latter organization began broadcasting in 1994.

"We are excited to begin our partnership with Wieden + Kennedy New York, an innovative and creative powerhouse that will help us build on the success of Fox Sports' marquee live events and growing momentum of FS1's studio programming," said Fox Sports evp of marketing Robert Gottlieb in a statement. "Our new partner shares our vision for the future of FOX Sports and will bring proven creative and strategic expertise to the network's impressive sports rights portfolio."

The announcement also comes at a time when Fox looks to assert a larger influence within the rapidly changing world of live sports. As the number of traditional cable subscribers drops and competition for ad dollars heats up, Fox and ESPN have become more direct rivals. Earlier this week, the two entities engaged in a minor messaging battle regarding their respective ratings.

ESPN has traditionally been a bigger spender when it comes to marketing. According to Kantar Media, ESPN's $35 million paid media total in 2015 was more than three times higher than the same number for Fox Sports. In the first nine months of 2016, ESPN spent just under $20 million while Fox spent only $4.5 million.

Various sources tell Adweek, however, that the amount of ESPN work assigned to W+K had declined in recent years before the contract between the two parties ended last month. The transition occurred without a formal review. Moving forward, the agency will promote all of Fox Sports' major properties, including its daily shows, with a specific emphasis on coverage of the 2018 World Cup.

"This is an opportunity for real partnership, with a brand whose culture is rich and inspiring," said W+K New York managing director Neal Arthur in a statement. On the agency's storied relationship with ESPN, he said, "ESPN was a defining client for Wieden + Kennedy New York and our entire network. We wish them the best."

"ESPN and W+K benefited from a long, fruitful relationship that resulted in breakthrough creative, most notably the iconic and enduring 'This is SportsCenter' campaign," said a spokesperson. "We appreciate their contributions over the years."

According to the representative, ESPN does not plan to launch a review seeking a new creative partner and will continue working with multiple agencies including its in-house shop CreativeWorks. ESPN will the continue "This Is SportsCenter" campaign with different shops handling creative duties.