The Detroit Lions that you knew yesterday could be entirely different than what you see tomorrow.



The stars — Calvin Johnson, Matthew Stafford, Ndamukong Suh — will still be around, but the supporting cast probably is going to be much different.



And it can all start coming down Tuesday after 4 p.m.



Not only can their remaining 21 unrestricted free agents begin signing contracts with other teams at that time, but the Lions can do the same with players they’ve possibly targeted, such as Miami running back Reggie Bush.



General manager Martin Mayhew has vowed to be more active in the free-agent market this year than he was a year ago, when Detroit signed no UFAs. But he’s still likely to be limited because of salary-cap considerations.



Four starters from last year’s opening-day lineup came to Detroit under Mayhew as unrestricted free agents. Receiver Nate Burleson (Seattle) and defensive end Kyle Vanden Bosch (Tennessee) were signed in 2010, and linebackers Stephen Tulloch (Tennessee) and Justin Durant (Jacksonville) arrived in 2011.



Vanden Bosch was released last month, and Durant could be leaving if he gets the right offer.



The Lions’ unrestricted free agents, besides Durant, feature defensive end Cliff Avril, cornerback Chris Houston, safety Louis Delmas and offensive tackle Gosder Cherilus. That’s five key pieces off a team that went 10-6 in 2011 and then 4-12 in 2012.



Some of the other contributing players who are UFAs include cornerback Jacob Lacey, defensive end Lawrence Jackson, defensive tackles Corey Williams and Sammie Hill, special-teams performer Kassim Osgood, tight end Will Heller, long snapper Don Muhlbach and kicker Jason Hanson.



Avril, whose production dropped off in 2012 after a stellar 2011 season, apparently is pricing himself out of a return to Detroit. The Cleveland Browns reportedly are one of the teams making a strong push to sign him.



The Lions undoubtedly want Houston back, but it appears he’s going to test the market.



Delmas, who has been hampered by knee injuries each of the last two seasons, was given a physical last week by the Lions to update his health status. He plans to check out his options.



The Lions apparently will let Cherilus go to the highest bidder while replacing him in the lineup by a younger, less-expensive player on the roster, such as Riley Reiff, Jason Fox (restricted free agent) or Corey Hilliard.



In the offensive backfield, the Lions seem to have set their sights on Bush to fill the void left by Jahvid Best’s brain injury.



Bush isn’t a workhorse or a star, but he could be a nice playmaking complement to Johnson. Bush would create mismatches and break some of the explosive runs that were sorely lacking last season.



The question, of course, is the cost. Arizona is also evidently interested. The Lions probably need to keep Bush’s salary in the $3-4 million range.



If the price escalates, Detroit might decide to use its limited resources to fill another hole at defensive end, cornerback or safety.



Dwight Freeney (Indianapolis) is 33 years old and has been hampered by injuries the last two seasons. Does he have another year or two left in him?



The Lions have a track record for going after some of coach Jim Schwartz’s former defensive players from Tennessee (Vanden Bosch and Tulloch, for instance).



There are two free-agent defensive ends on the market — William Hayes (St. Louis) and Jason Jones (Seattle) — who also were in Tennessee when Schwartz was the defensive coordinator there. Jones played in college at Eastern Michigan.



Reportedly, Detroit is one of the teams that has shown interest in San Diego cornerback Antoine Cason, just in case Houston departs.



The Lions also could go after a safety as a possible replacement for Delmas. Houston’s Glover Quin and the New York Giants’ Kenny Phillips are among the top candidates available.



NFL teams were allowed to begin talking with player agents Saturday, but no agreements are supposed to be reached with the UFAs of opposing clubs until Tuesday at 4.



One thing is fairly clear: It’s about to get very interesting in Allen Park.