That total doesn't include center Nick Hardwick, who had surgery on his left ankle on Wednesday and is expected to be out the next eight weeks.
"When you don't practice on Thursday, it gets tougher," coach Norv Turner said. "Shawne and Vasquez, I think we're going to try to see what they're able to do tomorrow. I don't know that L.T. would be ready to try to do anything tomorrow."
Tomlinson sprained his right ankle in the season-opening, comeback win at Oakland and missed last Sunday's home loss to Baltimore. Vasquez sprained a knee at Oakland and also missed the Ravens game. Merriman was hurt against Baltimore.
The Chargers (1-1) host the Miami Dolphins (0-2) on Sunday.
Tomlinson said his injury is getting better but he's not sure if he'll be able to play Sunday.
"Hopefully it just keeps getting better and I start to do a little bit more every day," Tomlinson said.
The 2006 NFL MVP, Tomlinson said he's not going to rush back from this injury like he has in the past, including last year when he sustained a toe injury in the season opener and kept playing. He was also plagued by a groin injury late in the season, which forced him to miss the Chargers' playoff loss to Pittsburgh.
"I'm not going to go through what I went through last year, you know, out there playing at 70 percent," Tomlinson said. "I'm not going to do that. I want to make sure it gets healthy and where I need it to be, and I can help this team out. We've got great depth right now."
Merriman said he'll practice on Friday.
"It's one of those things where you take as much rest as needed," Merriman said. "I don't really call it rest because I've been trying to rehab and make it as strong as possible."
Merriman said he's been running on the side and working out in the swimming pool at team headquarters. He has no sacks in two games in his return from knee surgery that cost him the final 15 games of 2008, plus the two playoff games.
Also missing practice were linebacker Antwan Applewhite (hamstring), rookie safety Kevin Ellison (illness), defensive end Travis Johnson (groin) and linebacker Brandon Siler (illness). Inside linebacker Stephen Cooper missed part of practice with a sprained ankle.