Larry Hill recognized the voice on the telephone in late April. But Hill -- an NFL referee the previous five years -- was stunned to hear what Hall of Fame coach Joe Gibbs had to say: He wanted Hill to join the Washington Redskins' staff.

"I knew it was him because I heard his voice so much on TV, but I was very surprised to get the call," Hill said yesterday. "I've never rooted for a team or been involved with one. But he was very persuasive in asking me to do it."

Soon, Gibbs and Gregg Williams, Washington's assistant head coach-defense, interviewed Hill at Redskins Park about becoming a full-time consultant.

Because no other team had hired a referee to become its replay official, Hill sought permission from the NFL and was given the green light. His duties include attending every game to advise Gibbs on replay challenges, overseeing the referees hired to work practices and tabulating all the penalties called in practice, looking for tendencies of individual players.

"The game has so many parts to it," Gibbs said yesterday. "It's good to have someone up there who has tremendous experience. Is it [a play] reviewable? Is it close? Sometimes it's close and we can't tell."

While Gibbs was on an 11-year hiatus from the NFL after retiring in 1993, the league instituted several significant changes, including replay challenges. Thus, Gibbs -- known for his innovative ideas when he coached from 1981 to 1992 -- made the unique hire to help him deal with the new rules.

The game has changed in other ways that affect Gibbs on game days. He now can talk directly to his quarterback, who wears a radio in his helmet. And he has five fewer seconds to get his team ready for each snap of the ball.

In Sunday's 16-10 season-opening victory over the Tampa Bay Buccaneers, Gibbs did not challenge the placement of the football that left his club with fourth and inches at the Tampa Bay 3-yard line. On third and one, quarterback Mark Brunell sprinted up the middle to escape pressure and appeared to slide inside the 2-yard line for a first down.

With the ball placed at the 3, Gibbs sent in John Hall to kick a 20-yard field goal that gave the Redskins a 10-0 lead. Gibbs said the overriding factor in his decision to go for three points was the risk of losing momentum, and that Hill didn't recommend a challenge. (Coaches make a challenge by throwing a red flag onto the field before the ensuing play.)

Yesterday, Hill held his daily meeting with Washington's coaching staff, detailing why he didn't tell Gibbs to challenge. Hill saw three replays but felt that the two camera angles used weren't sufficient to get the call overruled. The angles shown were with Brunell running toward the camera, plus a view from behind.

"The best angle to use is straight down the sideline, straight in, a 90-degree angle," said Hill, a replay official in last season's Super Bowl. "The TV didn't have that angle. We would have lost the challenge and the timeout."

Hill added that the yellow line shown on television indicating how far an offense has to go for a first down isn't official. "That's a TV product to help the fans know where the first-down line is," Hill said. "That was probably at least a half a yard off."

Although the NFL had an instant replay system during Gibbs's first stint, coaches weren't allowed to challenge calls. Whether a replay merited a review was left to an official in a replay booth. In 1999, the NFL permitted coaches to issue two challenges each game. If correct, the call is reversed. If incorrect, the team loses a timeout. The league tweaked its policy before this season: Coaches can still request two replays per game. If the team is correct on both challenges, the coach earns a third challenge.

Most NFL coaches give assistant coaches heavy input in making challenges. One factor in Gibbs hiring Hill was that coaches tend to become emotionally attached to plays. Despite replays, challenges are often split-second decisions that require neutrality.

Yesterday, wideout Rod Gardner was still convinced that he caught a pass early in the second quarter that was ruled incomplete. The Redskins had the ball on third and 10 from the 50-yard line. Brunell's hard pass bounced off Gardner's chest as the wideout fell, and he grabbed the ball near the ground. Gardner tried to get Gibbs's attention on the sideline by yelling, but the Redskins sent out their punting unit.

"They got away with that one," Gardner said, his voice still tinged with disappointment. "It was on replay. Plus, people who saw it on TV said it was a catch."

Hill chuckled when told about Gardner's response. "That one was very easy," Hill said. "Coach Gibbs saw that [yesterday]. The whole ball was laying on the ground."

Hill sits behind Redskins quarterback coach Jack Burns in a booth containing six Redskins assistants. They all wear headsets allowing them to communicate with Gibbs, but Hill generally sends his messages through Burns to reduce the number of voices.

One constraint in the setup is that the coaches in the booth must count on the network televising the game, seeing only one or two replays before the opportunity to issue a challenge. Replay officials see many more angles and can slow down the play or stop the frames before ruling on a challenge.

"We're at the mercy of television," Hill said. "Whatever television shows is what we have to go by. We might see it once."

Rick "Doc" Walker, who played tight end with the Redskins from 1980 to 1985, isn't surprised by Hill's hiring. He recalls that during Gibbs's first season as a head coach, the Redskins were the NFL's only team that had referees regularly working practices.

"I've always seen him do those types of things," Walker said yesterday. "He didn't reinvent the wheel. But he sure greases it up."

The NFL has reduced its play clock from 45 seconds to 40 seconds since Gibbs retired in 1993. Gibbs's offensive wizardry (his 1983 team set an NFL scoring record that lasted until the Minnesota Vikings broke it in 1998) partly came from quirky formations and movement before the snap. Thus, Gibbs considered the loss of five seconds significant enough to alter his pre-snap schemes. Gibbs faced a challenge getting the appropriate personnel on the field in time, and used the preseason games to adjust.

"That's a huge deal," he said. "I've always been in favor of more time between plays."

Gardner said: "Back in the day it was easier to do all that shifting and motion. In practice we were going 100 miles per hour trying to get it done."

One change that pleases Gibbs is the invention of the helmet radio allowing coaches to communicate with their quarterbacks. In Gibbs's first tenure, hand signals were used to send in plays, which could result in confusion, and was subject to opponents trying to steal signs. Despite Gibbs's penchant for secrecy, he is one of the few coaches who doesn't use a clipboard to cover his mouth when speaking into his microphone to talk to his quarterback.

"If they are going to read my lips then they can read my lips," Gibbs said, laughing heartily. "Most of the time I will probably be saying: 'You idiot. Hit the open guy.' So if they read some of that it will confuse them."

WORTH A SECOND LOOK?: Unlike during his first stint in the NFL, Joe Gibbs has the option of challenging plays called on the field. When Mark Brunell came up short of a first down on this play, the Redskins' coach -- with ex-referee Larry Hill advising -- decided not to.Despite penchant for secrecy, Joe Gibbs doesn't bother holding a clipboard over his lips when speaking into his microphone to talk to his quarterback. "Most of the time I will probably be saying: 'You idiot. Hit the open guy.' "