MARLBOROUGH — The Greater Keene 13 and under Babe Ruth youth baseball team had its back to the proverbial wall Saturday afternoon.

It trailed Exeter 3-0 going into the bottom of the sixth inning with a trip to the state finals on the line. But, in dramatic fashion, Keene rallied for five runs, took the win and punched its ticket to the championship round.

The fun, it turned out, was just beginning.

Exeter got its rematch a day later, fighting its way out of the losers’ bracket and into Sunday’s final. Its only drawback was that it needed to beat Keene, the lone undefeated team remaining, twice.

That didn’t happen. Instead, momentum from Saturday’s comeback carried over at the Marlborough School. The team lit Exeter up for a four-inning mercy-rule win, 18-0, in the first game to claim the state championship.

Keene earns a berth in the New England Regional tournament, which starts Friday in Stamford, Conn.

“I just feel like we came into this game feeling pretty good because we came back yesterday,” said Evan Gutkowski, who picked up the win on the mound Saturday after throwing three hitless innings of relief.

The offensive explosion started right away for Keene on Sunday, as the local entry scored 10 runs in the top of the first inning.

Casey Mooers got things started with a one-out double, then Brock Haynes singled and Joel Beard was intentionally walked to load the bases. Ted McLaughlin came up and connected with the first pitch he saw for a single, driving in Mooers and Haynes.

Jack Riendeau was hit by a pitch in the next at-bat, then Ben Dean hit an RBI single and Jordan Ketola drove in another run with a sacrifice fly to right. Ketola’s sac fly ended a streak of six straight batters reaching base, but Keene simply replicated the streak to put more runs on the board.

Otto McLaughlin and Cam Tinnin got back-to-back walks, bringing in another run, and were then followed by an RBI single from Gutkowski, a bases-clearing double by Mooers and an RBI single by Haynes. Beard also singled, before Ted McLaughlin ended the streak and the inning with a fly-ball out to left.

“We just had a good talk with them yesterday,” Keene Assistant Coach Jonah Ketola said. “The bats were flat for about four innings, and about the sixth inning they showed up, and then we said, ‘Let’s keep it going into today.’ ”

Between the two games, Keene scored in five straight innings, totaling 23 runs.

Keene managed just one run in the second, then hit around the order again in the third for six more runs, putting the team in range for a four-inning win.

Gutkowski reached on an error by the third baseman to lead off, then Mooers walked and Haynes was hit by a pitch to load the bases. Beard grounded into a fielder’s choice, but an error at short allowed Gutkowski to score the inning’s first run.

Ted McLaughlin and Riendeau followed with back-to-back RBI singles, then Dean grounded into a fielder’s choice that saw McLaughlin forced out at third and Beard come in to score. Jordan Ketola walked to reload the bases, then Otto McLaughlin and Tinnin wrapped up the scoring with an RBI single and RBI groundout.

Keene scored one last run in the fourth, but with how the defense was playing, it wasn’t necessary to preserve the mercy-rule win.

Tinnin (three innings) and Haynes (one inning) combined to shut down the Exeter offense, holding it to just three hits. The Keene fielders played error-free baseball, a stark contrast to the six errors committed by Exeter.

It was also an important contrast to Saturday’s game, in which Keene committed three errors resulting in three runs against starting pitcher Jordan Ketola, despite him giving up just one hit through four innings.

“If the defense is working well and we’re making our plays and not having any errors, the pitcher’s going to have an easier time on the mound, and today that’s what the boys did,” Coach Ketola said. “We had a few miscues yesterday; today we told them, ‘Hey listen, we can’t be having them errors,’ and right away they stepped up, the defense stepped up.”

The team now gets ready for the five-day turnaround before regionals.

Several of these players know what it means to play at a high level. Gutkowski is one of seven players, according to Ketola, who played on last year’s Cal Ripken 12 and under state championship team; meanwhile, players like Mooers, Beard and Luke Weber have won a state title on the ice with the Keene Youth Hockey program.

And if the momentum carries like it did from Saturday to Sunday, the team could be in for long and crazy ride in Connecticut starting later this week.

“I feel like we have a pretty good chance at going pretty far in that tournament,” Gutkowski said.