Ever since Jets quarterback Mark Sanchez injured his right (throwing) shoulder in an Aug. 24 preseason game against the Giants, the Jets and Sanchez have said little about the nature of the injury. Both said the injury was day-to-day, and Sanchez maintained that he was feeling better every day.

But the injury could be more serious than initially thought. Reports had classified it as a bruised joint, as the Jets turned last week to rookie Geno Smith to start Sunday’s opener against Tampa Bay.

Yesterday, before the game, ESPN’s Chris Mortensen reported that doctors believe Sanchez has a partially torn labrum, and that he will seek a second opinion from the renowned sports orthopedic surgeon Dr. James Andrews.

Meanwhile, Jay Glazer of Fox Sports reported Sanchez dislocated his shoulder when defensive tackle Marvin Austin hit him, and doctors popped it back in, but they want to make sure it stays in place before he can play.

Glazer’s report classified the injury as a partially torn labrum, and also noted that Sanchez has a shoulder subluxation, which is similar to a dislocation, except that a subluxation is temporary and partial, though still results in instability in the joint.

Jets general manager John Idzik has said Sanchez isn’t a candidate for injured reserve, but that could certainly change depending on what unfolds in the coming days.

** Five Jets left Sunday’s game with injuries, but all five returned.

Tight end Jeff Cumberland and wide receiver Jeremy Kerley took helmet-to-helmet hits that drew penalties. Receiver Stephen Hill was clocked by several Tampa Bay defenders at once and was helped off. And receiver Clyde Gates limped on the sideline after catching a pass and stepping out of bounds.

The most worrisome injury was to center Nick Mangold, the Jets’ best offensive lineman. He hurt his right elbow and went to the locker room, but returned with it wrapped up. Caleb Schlauderaff stepped in when Mangold was out.

** Probably the most impressive part of the Jets’ defensive performance Sunday, when they allowed just 250 yards, was the job they did against Tampa Bay running back Doug Martin, a second-year player who ran for 90.9 yards per game last season. The Jets limited him to 65 on 24 carries, an average of 2.7.

He had a 5-yard touchdown after Tampa Bay took over at the Jets’ 5 following a strip sack. Martin had a long run of 17 yards, as well. Take away that 17-yard run, and the Jets limited Martin to a 2.1-yard average on his other 23 carries. Jets defensive end Muhammad Wilkerson was happy to see Martin held well below 100 yards.

“That was one of the goals I wanted for myself and for the defense,” he said.