Sewell was a big part of the come back for Wyoming (5-10, 1-1 MWC), as the center scored 14 of her game-high 26 points in the second half comeback.
"She was just being aggressive and I was playing behind her," said senior Porche Torrance. "After that she made her shots."
The Cowgirls outscored New Mexico 32-20 in the paint and out-rebounded the Lobo women 48 to 34, including a 20-10 advantage on the offensive boards.
UNM opened the game on a 14-4 run and held the lead at 10 for much of the first half as forward Caroline Durbin shot 7-of-11 from the field, scoring 17 of her career-high and game-high 29 points in the first half.
"It felt really good," said Durbin. "Almost anything I shot felt like it was going to go in, and luckily it did. I felt like I had the hot hand, I guess. (In the second half) they stepped up their defense on me, so I tried to take my shots but also get my teammates involved a little more. They started to double me."
New Mexico led 28-20 at the half and looked to be in control with a 33-23 lead with just over 17 minutes left in the second half before the Cowgirls went on an 8-2 run to cut the lead to 35-31 with 13:44 left.
Durbin cut the run short with a three pointer with 13:16 left to make the score 38-31 but Wyoming managed another run to close to 39-34 mid way through the half.
UNM held a slim lead until the Cowgirls took their first lead of the second half 48-47 on a lay-up by Sewell with 1:31 left in regulation. UNM tied the game at 49-49 on a lay-up by Durbin but would get no closer.
"Well, 0-2 in the conference is not what you want," said Sanchez. "Last year we started 0-5, and that wasn't fun. It doesn't get any easier. It's a game we could've won. It's one of those games where you look back at the stats and boxing out was one thing, getting other people involved is another."
Torrance added 6 points and 10 rebounds. Emily Stark came off the bench to add 4 points.
The Lobo women next travel to San Diego State (12-4, 2-0) Wednesday for a 7 p.m. MST tip-off. The Aztec women defeated UNLV 66-62 in overtime Saturday afternoon.
The game will be broadcast on 610 AM, The Sports Animal.