CBS prides itself on stability, and its upfront presentations usually reflect that, with few bold moves and lots of shows getting renewed.

But with the network focusing more and more on adults 18-49, there could be one major change announced at tomorrow’s upfront presentation, and that’s Thursday stalwart “Without a Trace,” now in its fourth season and still growing, switching to creaky Sunday night.

Media researchers caution that CBS is notoriously tight-lipped with its schedule and that the move will depend in part on what ABC’s Sunday nights look like. It may also be nervous about "Grey's Anatomy's" surprise switch to Thursdays, and thus decide to protect the night by keeping "Trace" in place.

But there’s a good chance that CBS will ditch its long-steady “Sunday Night Movie” in an attempt to lure more 18-49s to one of its oldest-skewing nights. And if it does so, moving an established show there would make sense, if not "Trace," then another returning show.

“CBS has already renewed most of its current lineup for the fall. This leaves little room for new series,” says a midseason report from MediaVest. “The Sunday movie will likely be replaced by scripted programming.”

If that happens, and “Trace” is part of that move, expect it to perform well on Sunday night, especially with “Grey’s Anatomy” no longer dominating the 10 p.m. slot and fellow ABC drama “Desperate Housewives” slipping over recent weeks.

“If ‘Grey’s Anatomy’ is moved, ‘Without a Trace’ can move there, but it opens up the question of what [CBS] will partner it with,” says one media researcher. “I expect people will follow the show if CBS does move it.”

Of course if CBS president Les Moonves craves more stability, “Trace” will stay put.

There won’t be too many CBS scheduling moves. The network has very few holes, despite being slightly down year to year among 18-49s. With “King of Queens” staying on for 13 episodes, the night including “How I Met Your Mother,” “Two and a Half Men,” “The New Adventures of Old Christine” and “CSI: Miami,” will return untouched.

On Tuesday, “NCIS” and “The Unit” will stay put at 8 and 9. A similar testosterone drama, perhaps "Jericho, "Smith” or James Woods’ “Shark,” will join the lineup at 10 p.m.

Wednesday “Criminal Minds” and “CSI: NY” have both been renewed, but 8 p.m. has been problematic. The network could launch new comedies there. It probably won’t bring back “Amazing Race” in the slot, either bumping it to midseason or perhaps Friday or Sunday. It may also put some comedies there, with “The Class,” which already has a commitment, about a group of former third-grade friends, or "Big Bang" contenders.

If “Trace” leaves Thursday, where “Survivor” and “CSI” are expected to keep their 8 and 9 slots, that frees up another slot to launch a new drama. D.C. dramas “Company Town” and the untitled Kevin Pollack-Joshua Jackson project could be contenders.

Fridays may return intact, with “Ghost Whisperer” at 8 and “Numb3rs” at 10 both receiving early renewals. The 9 p.m. “Close to Home” will also return, with a late renewal yesterday.

Saturday will likely be crime drama repeats and “48 Hours Mystery.” “60 Minutes” and “Cold Case” will keep their 7 and 8 slots on Sunday, where there’s room to launch a new drama as well if “Trace” moves over.