By Tony Moss, NFL Editor -- (Sports Network) - The San Diego Chargers and Seattle Seahawks will kick off a busy week on Monday night, when the two former AFC West rivals face off at Qualcomm Stadium in the next-to-last preseason game for each team.

Just four nights after they meet in Monday's primetime affair, the teams will both be back on the field to play their preseason finales. The Chargers will travel to play the San Francisco 49ers on Friday night, while the Seahawks will host the Oakland Raiders.

Just hours after finishing those contests, both teams will have to reduce their rosters from 75 players down to the league maximum of 53, and will by Sunday have established an eight-man practice squad as well.

Given the impact of the tight timeframe on possible playing time for Friday's game, Monday's contest is likely to see the Chargers and Seahawks' starters see their last meaningful action until the regular season.

That said, San Diego is nearly certain to be without three of its highest- profile players in its final warm-up before the home fans.

Running back LaDainian Tomlinson has yet to play in the preseason, as is customary for the Pro Bowl running back.

Tight end Antonio Gates (toe) just recently returned to the practice field and is unlikely to be cleared for game action. Gates is expected to be ready for the regular season.

More concerning for the team, however, is a knee injury to linebacker Shawne Merriman that could reportedly be career-threatening. The Pro Bowler has a torn posterior cruciate ligament, and, at the very least, his status for the Sept. 7th opener against the Carolina Panthers is tenuous.

The Seahawks could also be without their most prominent player on Monday.

Quarterback Matt Hasselbeck has been bothered by a sore back, an injury that kept him out of last Saturday's 29-26 overtime win over the Bears.

If Hasselbeck can't go against the Chargers, Seneca Wallace would likely get the start with Charlie Frye coming off the bench. Frye played the entirety of the Bears win, completing 20-of-35 passes for 209 yards with three interceptions and no touchdowns.

Elsewhere on the injury front for Seattle, wide receivers Bobby Engram (shoulder), Deion Branch (knee), right tackle Sean Locklear (knee), and center Chris Spencer (back) are unlikely to appear against San Diego.

Seattle leads the all-time preseason series with San Diego, 5-3, including a 24-16 road victory prior to last season.