Both Hatch and Medeiros scored for the second straight game and gave the Cougars (6-3-2) their fifth straight win. The Mustangs fell to 5-6-0 on the season.
"SMU was very low pressure in the first half and we were having to play a lot more defense than we would have liked," BYU head coach Jennifer Rockwood said. "I told the girls that we've got to get back to those basics of working hard and playing harder. I thought the girls did a good job of doing that right from the kickoff in the second half."
It took 66 minutes, but Medeiros broke the stalemate with a pass from Michele Murphy that slotted her to the left side of the penalty area. Medeiros found an angle on the keeper and put it away for a 1-0 lead.
Hatch followed the assist with a penalty kick she earned going away from goal in the penalty area. She put it away for a 2-0 advantage. Three minutes later, Hatch found an opening off a pass from Medeiros and put it away for the final 3-0 margin.
In the first half, the Cougars outshot the Mustangs 5-3, but both sides put two shots on goal. Nimmer led BYU with three shots, putting one on goal. Nadia Gomes came on and immediately tried to flick a ball past SMU's keeper, but it didn't find the net.
It was also senior goalkeeper Katherine Snyder's second solo shutout of the season as she went all 90 minutes and held SMU scoreless on seven shots and three on goal. The Cougars finished with 15 shots and four corner kicks, as SMU finished with just seven and two.
"It feels good to get a couple wins on the road," Rockwood said. "We've got to get results from here on out, for sure, if we want to accomplish some of our goals."
BYU will being West Coast Conference play on the road against San Diego on Friday, Oct. 3 at 7:30 p.m. PDT.