NFL

CLEMENS CLIMBS

PHILADELPHIA – Chad Pennington’s preseason is over. If he plays a down the Jets’ preseason finale against the Eagles tonight, it’ll be an upset.

As for Kellen Clemens, tonight marks the end of his season . . . if all goes well for the Jets, that is.

Clemens, Pennington’s backup in his second season, has been a revelation this summer, not only cementing himself as the No. 2 but offering a positive glimpse into the future.

Though the bulk of his work has come against backups, Clemens has led the Jets on eight scoring drives (seven TDs, one FG) in 13 possessions. He’s 28 of 39 for 352 yards, four TDs and two INTs.

Those numbers, even if they had come in practice, are eye-opening.

“He’s establishing himself as a very solid NFL quarterback,” WR Justin McCareins said of Clemens. “He gets better every day. He’s a gutsy guy who has a big future.”

McCareins should know. Five of his six preseason receptions have come from Clemens.

“This is a big game,” Clemens said. “This will be the last time I have a good chance of playing. You want to go out there and finish strong.”

Another good showing tonight may have Jets fans clamoring for Clemens should Pennington struggle early in the season.

“It’s definitely a lot easier being in my second year,” said Clemens, a second-round pick out of Oregon. “The game is slowing down. In your second year, things should become more clear.”

Eric Mangini said he likes what he’s seen of Clemens from last year to this summer.

“He had a good training camp last year and, as you transition into the season, whether you’re the second or the third (team), you just don’t get the volume of reps that you would if you’re the first,” Mangini said. “You’re trying to prepare, but you don’t get that same level of experience.

“He would take a group after practice and those guys would run through plays together. It could be the practice squad receivers or some of the guys who may be on the third and fourth. Those things are huge in the development of any player.

“There are no shortcuts to improvement. It comes through hard work.”

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Mangini has an intriguing decision to make with the third quarterback spot as the final cut to 53 players looms Saturday.

One player who’s been a bit lost in the shuffle and will have a last chance to show his worth is QB Marques Tuiasosopo. Brad Smith as the No. 3 makes the most sense because of his versatility as a WR, RB and kickoff returner. Tuiasosopo said he hopes to use tonight to make the coaches believe he must stay.

“I’ll play hard and do the things that will hopefully be good for me to showcase what I can do to operate this offense,” said Tuiasosopo, a veteran who played in Oakland last season.

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All eyes will be on the precarious left-guard situation, with rookie Jacob Bender and Adrien Clarke battling to replace Pete Kendall. Bender, who had a rough outing Saturday against the Giants, will get another long look. . . . CB Justin Miller (hamstring) and S Eric Smith (leg) returned to practice during the week and are likely to play. Starting CB Andre Dyson, who sat out last week’s game against the Giants with a leg injury, also practiced but might sit as a precaution. . . . RB Thomas Jones, who’s played one preseason game because of a strained calf suffered on Aug. 12, won’t play but is expected to be ready for the Sept. 9 opener.

mark.cannizzaro@nypost.com