VASSALBORO — Kristen MacDonald felt the lead slipping away on the back nine in Tuesday’s 56th annual New England Women’s Amateur at Natanis Golf Course.

MacDonald, the first-round leader from Billerica, Mass., had a comfortable five-stroke lead over Sam Morrell shrivel away on the back stretch.

It was just two as they played the 18th.

“I knew she was playing well,” said MacDonald, “but I didn’t want anything that took me away from my game. I just wanted to finish strong.”

MacDonald, 23, did just that, dropping in a short birdie putt on the 18th to finish with a 3-over par 75 to grab a three-shot lead over Morrell heading into today’s final round on the 5,506-yard Tomahawk Course.

“I’d rather be chasing, but I was kind of hoping I’d be a little closer,” said Morrell, a North Kingstown, R.I., native and a senior at Old Dominion University in Norfolk, Va.

“It wasn’t meant to be. Kristen played pretty well. She made a lot of her putts. But I’m still lurking. I’m still in the mix.”

Jen Holland, of Branford, Conn., and Rita Bedard, of Sturbridge, Mass., are five shots back and tied for third.

Katie Partridge (155), Keely Levins (156) and defending New England Women’s Amateur champ Pam Kuong (156) follow.

Natanis members Dale Hannon and Marie Cates each enjoyed improved performances. Hannon shot an 85 after a 90 on Monday. Cates finished with a 78 after shooting an 81.

Natanis members Ashley Chubbuck (188) and Jennifer Durant (195) are also competing.

Saco native Emily Bouchard, the defending Maine Amateur champ, shot a 78 for a 159 two-day total.

She had the best round of any Maine golfer for a second consecutive day. She shot an 81 on Monday.

“I did a little bit better but I still left some shots out there,” she said. “I missed a few three-footers, and you can’t do that. I wanted to be a little bit better, a little bit lower.”

MacDonald had her short game working for most of the sun-splashed day.

She parred eight consecutive holes after hiccups on the par-4 fifth (double bogey) and par-4 sixth (bogey).

She saved par on two par-3 holes – the seventh and 11th. She worked out of bunkers on both holes.

“That par 3 (on 11) was huge,” MacDonald said. “Getting up and down out of the bunker was big. That was huge confidence wise.”

MacDonald had a five-shot lead over Morrell after 12 holes, but that’s when the gap narrowed.

Morrell, the 2010 New England Amateur champ, converted two 5-foot birdie putts on consecutive holes, the par-3 13th and par-5 14th, to chip away.

“I had a lot of catching up to do,” she said. “Those birdies got me going.”

MacDonald then bogeyed 16 and 17 as Morrell pulled within two shots.

On the 18th, MacDonald hit a good drive that left her about 110 yards from the hole.

She then used a wedge to come within inches of the pin.

“To bounce back like that gave me some confidence,” said MacDonald.