Eastin broke the NFL’s on-field gender barrier Thursday night, serving as the line judge for a seven-man crew working a preseason game between the Green Bay Packers and San Diego Chargers.

Wearing No. 27 on the back of her official’s uniform, Eastin was dwarfed by the players as she lined up in front of San Diego’s sideline and had a camera following nearly every move before the game.

The 42-year-old from Tempe, Ariz., seemed at ease in the spotlight, though, and had at least two players shake her hand right before the opening kickoff.

Though she wasn’t involved in many calls until late, Eastin stayed steady among the giants and the national spotlight, earning her stripes by receiving the ultimate officials’ compliment: It was almost as if she wasn’t there.

It’s no surprise.

She’s a referee in the Mid-Eastern Athletic Conference, college football’s second-highest level, and a 16-year veteran of officiating. Eastin got her NFL shot as a replacement official, among a group taking the place of the regular refs, who are locked out.

And now, she’ll have a place in the Pro Football Hall of Fame.

Well, at least her cap will; the one she wore Thursday night is headed to Canton.

Replacement officials are working games for the first time in 11 years. Beginning with six games Thursday, they’re scheduled to work 16 games this weekend.

The crew working the Hall of Fame game last Sunday had some shaky moments and the officials at Thursday’s game between Buffalo and Washington were booed after muffing a touchback call. That added to Eastin’s pressure of being the first woman to officiate an NFL game — in front of millions of viewers, no less, with the game on national TV.

Eastin is no stranger to breaking barriers, though.

A multiple national judo champion as a child, she started officiating high schools games, moved up to colleges and eventually to the MEAC, where she became the first woman to be a crew chief.

Eastin also owns a company called SE Sports Officiating, which trains officials in football and basketball.

Other than her size, Eastin seemed to fit right in before the game, chatting with the other officials, members of the chain crew and a couple of players. Chargers tackle Jeromey Clary and linebacker Antwan Barnes sought her out just before kickoff, shaking her hand and saying a few words before she ran down the sideline for the first time.

Eastin spent most of the first half straddling the line markers and keeping track of the time, without much action on her side of the field.

Things picked up in the second half, when she had to break up a small skirmish between players on a punt and whipped her flag to the middle of the field for a holding call late in the third quarter.

Eastin heard a few boos early in the fourth quarter from the hometown fans for a pass interference call on San Diego’s Corey Lynch — a call she appeared to get right — and later signaled touchdown when Green Bay’s Marc Tyler dived in from 1 yard out.

Eastin added final TD signal on a 1-yard run by San Diego’s Curtis Brinkley and was on the spot for a fumble recovery by the Chargers near Green Bay’s bench in the closing seconds, though she didn’t have to climb into the pile to make the call.

Eastin joins a small group of women to crack the officiating ranks at the highest levels of sports.

Violet Palmer, one of Eastin’s inspirations, began officiating NBA games in 1997 and is still in the league.

Bernice Gera became the first woman to work in baseball’s minor leagues, serving as an umpire in a New York-Penn League game in 1972.

Pam Postema umpired major league spring training games in 1989 and, thanks to a push by commissioner A. Bartlett Giamatti, made it up to Triple-A for six seasons. She was fired a few months after Giamatti’s death, filed a sex discrimination suit against baseball and settled out of court 5 1/2 years later.

The locked-out NFL Referees Association said earlier Thursday that Eastin should be barred from working any league games because she once participated in the World Series of Poker. Should she be hired permanently, Eastin would be barred from such events in the future as part of the NFL’s gambling policy.