<p>               FILE  - From left are 2018 file photos showing Houston Texans head coach Bill O'Brien and Tennessee Titans head coach Mike Vrabel. Vrabel spent the past four seasons working as an assistant to Houston coach O'Brien, including as defensive coordinator in 2017. Now the men square off Sunday, Sept. 16, in the first of two games as rivals now that Vrabel is a rookie head coach with the Titans. (AP Photo/File)             </p>
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