The All-Pro tight end is listed as doubtful on the Chargers' injury report. No player with that designation has played in a game for San Diego this season.
But Gates isn't ready to rule himself out just yet.
"I know it sounds like a tape recorder," Gates told The San Diego Union-Tribune on Friday. "We just have to wait to see how I feel."
Gates has never missed a game in eight NFL seasons, but injuries to his feet and ankle have put his status in doubt as the Chargers prepare for a key AFC game in Houston. Gates sprained the plantar fascia in his right foot during last weekend's 33-25 victory over the visiting Tennessee Titans. He previously had been playing through turf toe and a sprained ankle.
Gates leads the NFL with nine TD receptions this season. He has 40 catches for 663 yards, both team highs.
Gates was in so much pain Monday that a team trainer drove him on a cart to his car. He acknowleged that if he does play against the Texans, he won't know for sure until shortly before kickoff.
"Sunday morning may be an understatement this time," Gates told the Union-Tribune. "It might be an hour before the game now (although a decision must be made 90 minutes before kickoff). I know it's going to be tougher (to make a decision) than it was last week."
The Associated Press contributed to this report.