Ashley Thompson has essentially grown up on the basketball court with Aaries Reed, Sharmaine Robin and Brittany Eley. They have played pickup and summer ball together, and Thompson's McDonough team has faced the Westlake trio several times the past few seasons.

You would think Thompson knows the Wolverines' act down pat, that nothing they can do would catch the senior forward-center by surprise. Then, all of sudden, without any hint or gesture, Robin will throw a backdoor pass to a cutting Reed or Eley for an easy layup.

"We've been playing with Ashley Thompson forever," said Reed, a senior forward, "and there are still times when we're playing against her that we can do something that she doesn't know about. We just see each other, and we know where we're going."

Robin, Reed and Eley will be in Westlake's starting lineup for the third consecutive season. They know each other's practice habits, how each will respond in tight game situations, each other's strengths and weaknesses, and, perhaps most important, when to expect the unexpected. It's the kind of thing born out of years of experience -- the kind of thing that can only come from the right chemistry.

"It's like things that your brother or sister do," Thompson said, trying to explain team chemistry. "You just know what they're going to do in a certain situation.

"It can be frustrating because you can't do anything about it to defend it. It's a huge advantage."

Chemistry resonates louder in basketball than perhaps any other team sport, regardless of the level. With only five players per team on the floor -- as opposed to more than twice that number for soccer or football -- every player's role is crucial. It's not uncommon to see basketball teams have success despite lacking a true star. That's where chemistry enters the equation.

"If you look at the three things critical to success," Calvert boys' coach Rick Lagana said, "it's talent, effort and, maybe, even more important as the other two, is chemistry.

"Chemistry is people who like each other and like to play with each other and people who don't care if they score two or 20. You don't want to have little jealousies about who is taking shots. If you don't have [chemistry], you end up with petty jealousies and bickering."

Chemistry is particularly tough to build in high school sports because roster turnover is so frequent. Rarely does a core group of players carry a team for more than one season.

This season, though, chemistry figures to be a big talking point for many teams in the Southern Maryland Athletic Conference. The top scorers return on six boys' teams and six girls' teams, and most of them still are surrounded by the complementary pieces from last season.

Among the boys' teams, where there is no consensus preseason favorite:

* Calvert returns the conference's leading scorer, senior guard Eric Young, with two of the team's next three top scorers -- junior forward Mike Pernell and senior guard Seth Travers.

* Great Mills returns each of its top four scorers -- seniors Matt Leddy and Jimmy Moore and juniors Will Smith and Cody Kohn.

* Huntingtown returns its leading scorer -- junior forward Mark Smith -- and two of its top five, seniors Bryan Shearer and Ian Schwalenberg.

* McDonough brings back outside scoring threat Preston Faulk, who averaged 17.4 points last season, along with versatile forward Joe Respress.

On the girls' side, in addition to Westlake, which returns the entire starting lineup from last year's Maryland 3A semifinalist, it appears strong chemistry exists at:

* Thomas Stone and Northern. Each lost its leading scorer -- Shavon Knight and Amber Mullins, respectively -- to graduation, but both teams return their next four top scorers.

* Patuxent, which returns three of its top four scorers: junior center Chrissy Robinson, senior guard Tasha Klares and junior forward Kelsea Bullock.

* Calvert, which brings back the Washington area's leading scorer, senior center Whitney Johnson, as well as the team's starting back court of junior Lauren Robison and sophomore Michelle Buckmaster.

Watch each of these teams at the beginning of the season. Coaches and players agree that teams with so many critical parts returning don't have to struggle to define roles and learn their coach's system.

"You should usually be a couple of weeks ahead of everyone else at the start," Thomas Stone girls' coach Mark Gladfelter said.

Practice for these teams begins with players in midseason form with their X's and O's.

"It's critical in high school because of the restrictions and limited amount of time you have to practice together," Great Mills boys' coach Frank Peck said. "This isn't like college. In high school, you have to have that group that comes up together.

"It's allowed me to accelerate me putting in our system. I don't have to spend two, three practices on one half-court set."

And once games get going, teams with good chemistry don't freeze and wonder who will take control or worry about getting players ample looks.

"They're more confident, and they know what's going on," Huntingtown boys' coach Rick Weber said. "When you're new and you're out there, you're tentative and worried about what's going on.

"People talk all the time about team chemistry and having your best buddies on the team. I don't talk about team chemistry in terms of 'Do they like each other?' but [rather], 'Do they understand their roles on the team.' "

Players said they often recall moments from games past when they made a particular connection with a teammate on a play or two. They know where their low-post players like to set up and be fed the ball, or they know that on a fast break, a teammate might be better going left than right.

"It just comes from playing with guys for so long," Great Mills's Leddy said. "It's really tough to have if you don't have that experience. You kind of sense things before they happen, like I know when Cody [Kohn] is up top, he's looking for a cutter. He doesn't have to say it, so I'll just cut."

Although coaches preach on-court communication as an intrinsic component of team chemistry, the teams most in sync talk silently.

"I can just look at Sharmaine and Brittany, and they know exactly what I'm thinking," Reed said. "I don't have to say anything."

That's because they have said plenty to each other in the past. Lagana began last season with only one varsity veteran -- Young. This season he will start with nine.

"We started over last year," he said, "and hopefully we can reap the benefits of it this year."

Aaries Reed, left, and Sharmaine Robin, right, have been in Westlake's starting lineup the past two seasons with Brittany Eley. The Wolverines made the Maryland 3A semifinals last season.Calvert guard Eric Young, right, led the Southern Maryland Athletic Conference in scoring last season. Junior forward Mike Pernell and senior guard Seth Travers, two of the team's top scorers, also will return, giving the Cavaliers the necessary experience to compete for a SMAC title. Junior Mark Smith (44) was the top scorer for Huntingtown last season. The Hurricanes also will be bolstered by the return of seniors Bryan Shearer and Ian Schwalenberg.