At first glance, the coast seemed clear and DeMatha’s Linwood Ruffin had enough room in transition to score a basket and cut into O’Connell’s lead during the third quarter of their Washington Catholic Athletic Conference clash Friday.

But as Ruffin lofted his shot, in soared long-armed Knights forward Junior Etou, who smacked the ball out of bounds before wagging his index finger with a grin in homage to former NBA star Dikembe Mutombo.

Friday proved to be that kind of night for No. 6 DeMatha.

Open looks either rattled off the rim or were thwarted by O’Connell’s tough defense. The second-ranked Knights took advantage and coasted to a 68-48 victory in Arlington to snap DeMatha’s seven-game win streak.

Melo Trimble paced O’Connell’s attack, scoring a game-high 21 points in a performance that the junior hopes will give him a break from his teammates.

Melo Trimble scored 21 points and Junior Etou had nine points and 19 rebounds to lead O’Connell to a win in a WCAC battle. (Nick Plum for Synthesis/Koubaroulis LLC/The Washington Post)

“Guys on the team are always telling me, ‘Melo, we need you to do something tonight, we need you to do something,’ ” the Maryland recruit said. “The last few games were disappointing with me not scoring as much as I usually do and they let me know that, so it was good to get going some tonight.”

The Stags (7-4, 4-1) established themselves early with several steals and transition buckets to open a 10-6 lead. But DeMatha’s shooting quickly went cold, giving the Knights time to settle into their offensive flow.

Trimble scored eight points during a 22-2 run that saw DeMatha go nearly 10 minutes without a field goal in a span of the first and second quarters. A flurry of baskets led by Jairus Lyles (13 points) and Alani Moore (11 points) gave the Stags some momentum, but it was the Knights (14-1, 7-0) who came out strong in the third to bolster their 34-26 halftime lead.

In the third period, Leroy Butts scored six of his 14 points while Etou (13 rebounds) dominated the boards to eliminate second-chance opportunities for DeMatha. The Stags continued to struggle with their shooting; along with foul trouble for senior BeeJay Anya (seven points, six rebounds), it resulted in just seven points in the quarter and extended O’Connell’s lead to an insurmountable 19 points.

“We talk about stirring the defense and I thought we did an excellent job of moving DeMatha’s defense around by executing our offense well and showing them different looks,” Knights Coach Joe Wootten said. “DeMatha is very talented and has great size, so the goal was to defend well inside and use rebounding and good offense to get control of the game, and I thought we did that.”