The San Diego Chargers will be without Antonio Gates for their Week 2 matchup with the Tennessee Titans.

The Sideline View’s Adam Caplan reported the news via Twitter.

Wow, surprising. TE Antonio Gates in inactive for the Chargers along with RB Ryan Mathews.

— Adam Caplan (@caplannfl) September 16, 2012

Gates briefly left the Chargers’ Monday night game against the Oakland Raiders last week with a rib injury. He returned and finished the night with four catches for 43 yards.

As CBSSports.com’s Dan McLellan notes, Gates has 597 career catches, and will be just the fifth tight end in NFL history to record 600 catches when he reaches the milestone.

But Gates and Chargers fans will have to wait at least one more week for that momentous occasion. San Diego will sorely miss Gates, who has been quarterback Philip Rivers favorite target for the past several seasons.

Gates is an eight-time Pro-Bowler and has been named to the NFL All-Pro team five times in his career. He also made the All-Decade Team for the 2000s.

Gates has led the Chargers in receptions in seven of the past eight seasons, and has excellent chemistry with Rivers. The tight end’s size and athleticism make him a nightmare to guard, and Rivers rarely hesitates to put the ball up for grabs when Gates is in one-on-one coverage.

Ryan Mathews is also out this week, and Vincent Jackson and Mike Tolbert left the team this summer. This leaves Malcom Floyd as the only active player this week who ranked in the top-five in targets for San Diego last season.

Rivers will have to trust people who he is not used to throwing at, and the Chargers will need new faces to step up this week to have success in the passing game.