Impressive defensive play is also making a difference.The freshmen duo will try to keep the Wolfpack perfect and help the program to its first victory over Massachusetts in the semifinals of the Puerto Rico Tip-Off on Friday night.Purvis and Warren were considered to be among the top high school recruits in the country, giving North Carolina State (2-0) an impressive tandem entering this season.So far, they're living up to the hype.Purvis has totaled 28 points on 10 of 18 from the floor and 6 of 8 from 3-point range through two games.After a relatively quiet game in his collegiate debut, Warren scored 22 points in Thursday's 72-55 win over Penn State. Purvis added 12 points and hit all three of his 3-point attempts."T.J. and Rodney gave us a great scoring lift when we needed it in the first half," coach Mark Gottfried said.While Purvis and Warren are leading the way offensively, the Wolfpack have also been helped by a strong defense. They've held opponents to 57.0 points per game and 30.2 percent shooting, including 22.2 from beyond the arc.Gottfried was mostly pleased with his team's play against the Nittany Lions."It was a good, physical game," he said. "It's good for us to play a strong, physical team that will challenge us around the basket and Penn State did that. Defensively, at times, we were very good. And, at times, we were disinterested defensively."North Carolina State is the only ranked team in this eight-team tournament, but it's lost all three meetings with UMass (2-0). However, the most recent matchup came on January 1, 2003.The Minutemen have already proven their ability to win close games, taking their first two by a combined five points.Terrell Vinson tipped the ball into the basket as time expired to give UMass a 77-75 win over Providence in the opening round of this tournament Thursday. That came two days after Sampson Carter hit a 3 in the final seconds to secure a season-opening 67-64 win over Harvard."I just don't want this to become a habit -- where you let a lead get away and have to win at the end," coach Derek Kellogg said.Jesse Morgan has been the team's top offensive threat, scoring 18 points against the Friars after he had 19 in the opener. He averaged 9.9 points as a sophomore last season.Fellow guard Chaz Williams -- the team leader with 16.9 points per game last season -- scored 17 on 7 of 13 from the field Thursday.The winner of this game will play either Oklahoma State or Tennessee for the tournament title on Sunday, with the losing teams meeting in the consolation game earlier in the day.