Breathing room at the top of the Patriot League standings is what Boston University craved, and that’s what it earned with a 71-62 victory over American last night at Agganis Arena. Maurice Watson Jr. had 13 points, seven assists and four rebounds, and the Terriers pounded the offensive glass for 16 rebounds, leading to 14 second-chance points, to give themselves a two-game cushion with three games left to play before their first Patriot League tournament. With its fifth straight victory, BU (20-8, 13-2) secured its first 20-win season since 2004-05. American falls further back in second place to 15-11, 11-4. “We looked at it as another game. We definitely wanted to beat them, revenge, for what they did to us down there,” senior Dom Morris said, referencing the Terriers’ 30-point loss at American in January. “We didn’t want to get too hyped. I felt we were a little too hyped in the beginning.” American built a 10-point lead 10 minutes into the game last night but the Terriers finished the half on an 8-0 run to cut the deficit to 32-31 going into the break. BU changed things by getting defensive stops and using its transition game to get easy buckets. “As the game wore on we just kind of kept coming,” Terriers head coach Joe Jones said. “Then we kind of had a breakthrough at that time.” The Terriers held American to 35.7 percent shooting from the floor in the second half and forced several crucial trunovers. Watson found John Papale for a straightaway 3-pointer for a 40-36 lead with 15:35 remaining. Later, a Watson jumper and Morris free throw capped a 15-5 run to push the lead to 48-39 with 10:37 to go.