SANTA CLARA, Calif. -- Once again, the San Francisco 49ers will be facing a dynamic young cornerback.Tennessee Titans cornerback Alterraun Verner is quickly turning into one of the best cornerbacks in the league. He has strong coverage abilities and already has four interceptions this season. Verner, 24, is a top reason why the Titans' defense has been strong this season.That will be a challenge for the 49ers who don't have much in the passing game behind Anquan Boldin and tight end Vernon Davis.