R.J. Barrett had 24 points and 13 rebounds to lead Montverde to a 74-61 defeat of Shadow Mountain on Thursday in a quarterfinal at the DICK’S Sporting Goods High School Nationals.

MIDDLE VILLAGE, N.Y. — R.J. Barrett had 24 points and 13 rebounds to help Montverde Academy (Montverde, Fla.) hold off upset-minded Shadow Mountain (Phoenix) 74-61 in the first quarterfinal Thursday at the DICK’S Sporting Goods High School Nationals.

Montverde opened the game as if it would blow out the Matadors, leading 21-6 at the end of the first quarter. Shadow Mountain, however, played like a No. 10 team in the second quarter, going on a 10-0 run to take the lead and the Matadors led 37-36 at the half. The Eagles gradually pulled away, however, while out-rebounding Shadow Mountain 45-21 for the game.

RELATED: DICK’S Nationals schedule and results

• (4) Findlay Prep (Nev.) 77 vs. (5) Oak Hill (Va.) 65
• (2) IMG Academy (Fla.), 40 vs. (7) Greensboro Day (N.C), 59
• (1) La Lumiere (Ind.), 64 vs. (8) Wasatch Academy (Utah), 52

“I’m proud of our guys.” said Shadow Mountain coach Mike Bibby, who played 14 seasons in the NBA. “We fought hard. I think our guys ran out of gas. This team doesn’t play in that type of atmosphere every day, like some of the teams here. We might have been overwhelmed at first and we calmed down. I don’t know if we were content with being up at the half.”

Montverde coach Kevin Boyle said having an early lead may have led his players to relax too soon.

“Obviously, (Shadow Mountain) shot the ball very well in the second quarter,” Boyle said. “I thought we guarded really well in the first quarter. Sometimes the worst thing to do in these things is have an early lead. We don’t zone that much and we zoned the whole second half and that was obviously effective. I am hoping the third quarter is more of what we are than the second quarter.”

Montverde (25-4) may have come into the game feeling disrespected because the No. 8 Eagles were ranked lower than four teams they have wins over: Findlay Prep (Henderson, Nev.); IMG Academy (Bradenton, Fla.); Memphis East (Memphis); and Bishop Montgomery (Torrance, Calif.). The Eagles also have several highly recruited players, including Barrett, a Canadian wing considered the top sophomore in the country, senior power forward Sean Mobley, who has signed with VCU, junior small forward Rechon Black, who has committed to North Carolina and a group of international talents, including Sandro Mamukelashvili, a power forward from the Republic of Georgia and Canadian sophomore guard Kevin Nembhard, who did not play.

After Barrett, the Eagles were led by Mamukelashvili, who had 20 points and 10 rebounds.

“I think their quickness bothered us,”  Mamukelashvili said. “They had a great point guards who were good in traffic. The main point for us was to help on defense and push the ball. We had a lot of mismatches and whoever had to guard R.J. was usually a mismatch. Our job was to get the ball inside.”

Shadow Mountain (27-1) came in with an unbeaten record, but as the only public high school in the event, may have also felt it had something the prove. Jovan Blacksher led the Matadors with 20 points with fellow guard Marcus Shaver scoring 19 points.

The Matadors outscored opponents 84.7-52.6 this season, but one of their best players, Jaelen House, had to sit the game because of a suspension after being ejected in Shadow Mountain’s state championship win.

“It’s unfortunate that he didn’t get a chance to play in a game like this,” Bibby said. “People might have a vendetta against me and took it out on him. It’s just upsetting.”

The Matadors also didn’t have a win over another Super 25 team and had played only one out-of-state opponent, West Linn, Ore., which lost this year in a 6A state semifinal.