MERRIMACK — Junior Emma Pfeifer came to the rescue for the Merrimack High School softball team on Wednesday.

Tomahawks star pitcher Emma Camberlain suffered a right-hand injury in the third inning, but Pfeifer pitched the final five innings and gave up only one run during a 5-3 win over Londonderry in the first round of the Division I tournament.

“It was a huge spot for Emma to come in,” said Tomahawks coach Greg Cochrane. “As of late, we have not been using Pfeifer a lot, but the kid practices hard. She is mentally prepared and ready. She delivered and pitched a gem when we needed her the most.”

Eighth-seeded Merrimack (12-7), which rallied from a pair of one-run deficits, will travel to top-seeded Exeter for a quarterfinal-round matchup on Saturday at 4 p.m.

Pfeifer was able to get out of a bases-loaded jam with no outs in the fourth, and then after the Tomahawks took a 5-3 lead with a two-run sixth, she was able to blank the Lancers in the seventh, getting out of a bases-loaded jam with two down.

Sophomore Erin Knauer went 3 for 3 for Merrimack with two doubles, a single and two runs, while senior Brenna Davenport (2 for 3, two doubles, RBI) and junior Kaeley Blades (2 for 2, double, single) also starred.

Junior Giovanna Komst, senior Delaney McGurn and freshman Olivia Chau all finished 2 for 3 with a double, single and a run scored for Londonderry (11-8). Junior pitcher Jilian Glynn was tagged with the complete-game loss, giving up 10 hits and five runs, with four earned.

Merrimack led the hits category, 10-9, as the hosts made one error and visitors were charged with two miscues.

Trailing, 3-2, heading into the bottom of the fifth, Merrimack started off with a double down the left-field line by Knauer. During the next at-bat, Davenport slammed a one-run double to left, which reached the fence in the air and evened the game at 3-3.

Pfeifer posted a crucial 1-2-3 sixth, and then in the bottom half of the inning, Blades led off with a double to left-center. A single by senior Jessica Trahan put runners at the corners with no outs. Freshman pinch runner Ashlynn Cassetty scored the game-winning run on a wild pitch during the ensuing at-bat. A sacrifice fly to left by senior Ashley Turcotte plated freshman Morgan Goodspeed with an insurance run.

“I could not be prouder of the way the kids played today,” said Cochrane. “We knew it was going to be a battle. We were engaged every pitch. Luckily, we were able to pick up those base hits when we needed.”

Merrimack struck first on an RBI ground out to second by Camberlain in the first. Londonderry answered, taking a 2-1 lead in the second on a two-out, two-run single by sophomore Aliceyn Lacey.

Merrimack knotted the game at 2-2 in the fourth with an unearned run by Cassetty, and then in the fifth, Londonderry claimed a 3-2 lead on a one-out, RBI double down the left-field line by senior Alyssa Vaillancourt.