It was just one game, but Monday night’s season opener provided a taste of what Boston College Football hopes to become under new head coach Bill O’Brien.

The Eagles, who entered the game as 16½-point underdogs, played disciplined, energetic and polished football and defeated No. 10 Florida State 28-13 at Doak Campbell Stadium in Tallahassee, Florida.

“Everything we did this offseason led to this,” BC quarterback Thomas Castellanos said. “This is what we were preparing for. It all worked out for the best.”

Former BC stars — from Matt Ryan to Doug Flutie and Zay Flowers — took to social media to express their overwhelming approval as BC continued to be a force to be reckoned with in front of a national audience.

Two years after a 44-14 drubbing of FSU on the same court, the teams turned the tables in this one, with Boston College earning its first win over the Seminoles since 2017, and its first season-opening victory over a ranked opponent since 1976.

“I’m very proud of these guys,” O’Brien said. “They were resilient tonight. To come out here and play a team that, in their eyes, really needed this win is a great statement for BC. But it’s just one win. It’s just one. We have to understand that.”

The Eagles crushed the hosts up front, rushing for 263 yards on 52 carries (5.1 average). They held the ball for just over 39 minutes, completely dominating the line of scrimmage on both sides, as FSU managed just 21 yards rushing on 16 carries.

BC (1-0, 1-0 ACC) took control from the opening whistle, amassing 102 yards, compared to just 4 for Florida State, and possessing the ball for all but 51 seconds of the first quarter. The Eagles leaned on their veteran offensive line to total 69 rushing yards, while the Seminoles (0-2, 0-2 ACC) failed to record a single yard on the ground.

Castellanos (10 of 16 passing, 106 yards, 2 TDs; 14 carries, 73 yards, 1 TD) gave the Eagles a 7-0 lead on the opening drive of the second quarter, accelerating from 4 yards out and diving headfirst into the end zone.

O’Brien raved all offseason about Castellanos’ growth as a decision-maker and passer, and it was easy to see why. Castellanos’ creativity and O’Brien’s discipline have a chance to form a dangerous combination.

The BC defense forced another three-and-out, then Castellanos hit former FSU running back Treshaun Ward (12 carries, 77 yards; 3 catches, 61 yards, 1 TD) for a 42-yard gain down the right sideline. Moments later, he found Ward for a 13-yard TD strike to put the Eagles ahead, 14-0, with 9:58 left in the half.

“In the back of our minds, it’s always nice to be able to have a little revenge on one of your teammates,” running back Kye Robichaux said.

Khari Johnson (4 tackles) and the BC defense came up with another three-and-out. At one point, Boston College had 174 yards to Florida State’s 8. The Seminoles didn’t get a first down until 6:13 into the second quarter.

With FSU getting going, Boston College star Donovan Ezeiruaku (4 tackles, 2 sacks) recorded a key sack and Kam Arnold broke up a pass in the end zone to limit the Seminoles to a field goal. Ryan Fitzgerald scored from 31 yards out to cut the lead to 14-3 with 5:05 left.

The Seminoles had a chance to make a significant dent, but quarterback DJ Uiagalelei missed several wide-open receivers. FSU had to settle for another field goal, this one from 24 yards with 25 seconds left, and the Eagles took a 14-6 lead into halftime.

Boston College held the ball for more than 21 minutes, held the Seminoles to 10 rushing yards and finished the first half with 6 of 9 third downs. Yet FSU trailed by just one score at halftime.

BC went the entire half without a penalty, after racking up a record 18 in a near-smash against Florida State last year. The Eagles were better than the Seminoles in many ways that half, but the penalties were severe and robbed them of a program-changing win.

“We’ve got to be a disciplined football team,” O’Brien said. “We’ve got to be a balanced team, a resilient team. I’m a big believer that helps you win football games.”

BC quickly regained momentum in the second half. FSU elected to try it on fourth-and-5 from its own 47, and Max Tucker intercepted a floating Uiagalelei pass and ran it back 58 yards. Two plays later, Castellanos Robichaux (19 carries, 85 yards, 1 TD) hit for a 4-yard score to extend the margin to 21-6 with 11:58 left in the third.

Kentron Poitier scored a 29-yard score for FSU, then Robichaux scored again — this time on the ground from 2 yards out — to give BC a 15-point lead after three quarters.

“Boston College should be known for its offensive line,” O’Brien said. “We have a great tradition of offensive linemen here, and hopefully these guys can continue that. They started off great tonight.”

The Seminoles were no longer a threat in the final period and BC decided the game in the fourth period, securing their trademark away win.

“We’ve got to be able to handle success the same way we handled adversity tonight, handle it the same way,” O’Brien said. “We’re on the right track. That’s for sure.”