Westminster and Lovett volleyball play together just fine, as it turns out.

The Wildcats’ Mason Rooney and the Lions’ Harley Sebastian, both rising sophomores, are on opposite sides of the net in high school, but the two play together during the summer for the 15-Mike team in the Atlanta A5 Volleyball Club in Alpharetta.

The club travels to the USA Volleyball Junior Girls’ National Championships Tuesday through July 5, after earning a berth with a third-place finish at the Midwest qualifier in Indianapolis in March.

Lovett and Westminster’s rivalry goes back well before these two were born, so they know how it is.

“You have to beat each other,” Rooney joked regarding games between the Lions and Wildcats.

That being said, making the same elite A5 team and living in the Buckhead area turned the girls into carpool buddies, fast friends and strong competition for one another.

“It’s good for Harley to be matched up against Mason, because it’s two [tall] kids,” 15-Mike coach Mike Webster said. “They help each other competitively because they’re both good blockers and have to pay attention to where the other is when they’re attacking.”

Both players shined as freshmen, with Sebastian, a converted outside hitter, being named to the 2011 Frosh 59 as one of the best freshmen varsity players in the nation.

At Lovett, with several upperclassmen choosing to focus on basketball and skipping the volleyball season, Sebastian had to move from the middle to an outside hitting position and led the Lions with 280 kills.

“I really had to step up to replace them,” Sebastian said. “I used to be a middle [hitter], and this was a new position. It was different, but I really like it. It’s fun and you get to play all the way around.”

Rooney, a right-side hitter, played a key role for Westminster, which reached the 2011 Class AA/A quarterfinals.

Rooney also made the cut for the U.S. Girls’ Youth Continental Volleyball Team competing in the USA Volleyball High Performance Championship July 24 through 28 in Des Moines, Iowa. She sets for the A5 squad, in addition to playing right side.

They both expect they’ll be called on to be on-court leaders, even as sophomores, when their high school campaigns get back under way. Sebastian is unable to compete at nationals next week because she suffered a broken ring finger on her left hand while blocking a shot during practice June 13, but she’ll be fully healed by the fall, when Lovett and Westminster are rivals yet again.

In the meantime, though, they enjoy the tight-knit atmosphere of the 15-Mike team, with eight of the 11 girls having been together for two years now.

“If you were to throw us out with random people from random teams, it would be different,” Rooney said. “But our team’s so close that it’s natural.”