In every sport there are tricks of the trade to provide an advantage.

In football, offensive lineman grab a certain spot under the armpit to mask holding.

In baseball, pitchers sometimes bite the ball to raise the seams, allowing for easier grip to throw breaking pitches.

And, apparently, in basketball some players grow out their fingernails to serve as a weapon.

“It’s an advantage at times,’’ said Trail Blazers guard Andre Miller, an 11-year veteran. “I did it a couple of times just to irritate somebody. I think every player has thought about that, letting them grow and possibily getting a couple scratches in and irritating someone.’’

Miller said the most notorious nails in the NBA are from Detroit guard Richard Hamilton, a notion that Martell Webster seconds.

“Yeah, I’ve seen his. They are nasty,’’ Webster said.

The Blazers play Hamilton and the Pistons on Saturday in Auburn Hills, Mich., and you can bet Miller isn’t thrilled.

“Richard Hamilton has some nails,’’ Miller said. “I get scratched up every time I play him. Everywhere.’’

Miller says he can only take so much during a game.

“I’ve seen a couple guys play with long nails, and I tell them in the game after a while that they have to cut their nails,’’ Miller said.

Nobody knows scratches on the Blazers more than Brandon Roy. The All-Star estimates he has at least 30 scars on his body from fingernails, and some of the scars are strikingly hideous. It has reached the point where Roy now uses a special cream to help with the scarring.

The largest scar, where his left shoulder and pectoral muscle connect, is jagged and raised, and looks as if he had surgery.

“People think I’ve had stitches there,’’ Roy said. “But it was just (Utah’s) Paul Millsap last year.’’

This season, Roy has been scratched so badly that the game had to be stopped several times to stop the bleeding. One time it was because of a scratch from Memphis guard O.J. Mayo, and another was from Lakers’ guard Kobe Bryant.

The scratches from Mayo and Bryant were on his chest, and happened in successive games. They hurt so badly that for a week Roy had to tell assistant trainer Geoff Clark to not touch his chest while he stretched him before games.

Roy said scratches are inevitable during a season, but when it starts to happen regularly in a game, players will speak up.

“I did against Memphis,’’ Roy said. “I was like, ‘O.J. man, you are killing me, man.’ ’’

Roy says there are two signs that tell him when to trim his nails: If an opponent complains, or if his nails get so long that he can hear them “click” on the ball when he is shooting.

LaMarcus Aldridge, who had the longest nails on the Blazers before Wednesday’s game in Philadelphia, said he too clips his nails using the guideline of hearing his nails “click” on the ball.

“I cut them, but they grow back fast,’’ Aldridge said. “I guess it’s because I drink a lot of milk, you know, all that calcium.’’

Webster, on the other hand, habitually bites his nails.

Roy says he doesn’t hear many complaints about his nails because of the way he plays defense.

“I’m not a real hands-on defense guy,’’ Roy said. “I’m not a big reacher. Usually the guys who scratch are big reachers or gamblers. Those guys get in there and take some skin off.’’

On Monday in Washington, Roy sat out the game with a sore hamstring. As his teammates showered and got dressed after the game, Roy went to the trainer’s room and groomed his nails. The result was a startling pile of nails.

“Oh yeah, mine grow, and they grow fast,’’ Roy said. “But I never think about it. That day it was more out of boredom. I didn’t have anything else to be doing at that time.’’

Roy said the most complaints happen during practice. As a result, he said the Blazers over the years have an informal training camp rule.

“Guys in training camp keep them down because you are going against your own team,’’ Roy said. “But in the season, against other teams ... I don’t care about other teams.’’