Answer to the above question: The first player Mills represented was Estes Banks, a CU running back that the Oakland Raiders chose in the eighth round of the 1967 NFL draft.

Source: https://www.dailycamera.com/2023/06/25/opinion-jim-martin-boulders-jack-mills-has-made-immeasurable-contributions-to-the-sports-industry/

But there was only one true rivalry back in that day, and it was the Pittsburgh Steelers and Oakland Raiders.

Source: https://steelersdepot.com/2023/09/steelers-spin-texas-two-step/

The Golden State Warriors moved across the bay to San Francisco in 2019, then the Oakland Raiders relocated to Las Vegas the next year.

Source: https://www.mymotherlode.com/news/state/3228464/manager-bob-melvin-returns-to-oakland-now-guiding-the-san-diego-padres.html

Their last win overseas was in 2014 against the Oakland Raiders.

Source: https://www.sun-sentinel.com/2023/11/04/game-time-fast-facts-odds-injury-report-and-key-info-for-dolphins-vs-chiefs-in-germany/