One of the biggest stories of the new season has been the sluggish performance of second-year shows that lost their mojo after being sidelined last spring due to the writers strike.

But while the future looks rather bleak for the likes of ABC’s “Pushing Daisies” and NBC’s “Life,” there are a couple of soph skeins — both airing on Monday night — that are thriving in season two.

CBS comedy “The Big Bang Theory” and CW drama “Gossip Girl” are the only titles among this year’s 11 sophomore skeins to improve their ratings vs. last year. And while they may garner smaller numbers than the shows that follow them on their respective nets, they deserve a lot of credit for opening the night so well.

For CBS, “Big Bang Theory” has been a strong performer at 8 o’clock, teaming with fourth-year show “How I Met Your Mother” to significantly upgrade the net’s performance in Monday’s leadoff hour.

Through the opening month of this season, according to Nielsen, “Big Bang” has increased its 18-49 rating by 6% vs. this time last year (3.7 vs. 3.6) even though it had launched in the higher-watched 8:30 half-hour last year.

Its strength in the important leadoff spot has enabled CBS to keep “Mother” at 8:30, where it has flourished over the past year, rising 24% vs. its showing in the lighter-watched 8 o’clock slot.

Together, the 8-9 p.m. combo for CBS is averaging a 3.9 rating — up 15% from last year and helping the Eye gain ground on slot leader “Dancing With the Stars” on ABC, which is down this fall.

CBS is now a strong No. 2 among the broadcasters for the hour, comfortably ahead of a pair of other sophomore series: NBC’s “Chuck” and Fox’s “Terminator: The Sarah Connor Chronicles.”

For CW, “Gossip Girl’s” ratings lagged behind its buzz during its frosh season, but that gap has been closing this fall. It’s still garnering oodles of press coverage for its attractive, young cast, but it now has the ratings to justify it.

The sudser about upscale New York teens is off to a nice start in season two, teamed with resurgent vet “One Tree Hill” to form the signature night the net has been looking for. And because it’s Monday, the shows serve as a promotional platform for the CW offerings on Tuesday, Wednesday and Thursday.

“Gossip Girl’s” racy, controversial — and some might say desperate — summer ad campaign seems to have worked in attracting new viewers. Through the season’s first month, “Gossip Girl” was up 23% in 18-49 vs. its showing on Wednesday a year ago and by a bit more in 18-34.

It has also consistently been first or second in its timeslot among females 12-34, the CW’s core aud.

“Gossip Girl” has helped energize “One Tree Hill,” which is up a robust 26% vs. its first month of last season (when it bowed in January) and is the net’s top-rated scripted show in 18-49 and 18-34. In recent weeks, the sixth-year skein has achieved or approached series-best scores.

“Hill” is having a strong year creatively, but it may not have picked up in the ratings if not for the “Gossip Girl” gang, which is now strong enough to open a night of its own.