Ronnie Lester, Iowa's 6-foot-2 do-everything guard with the bad knee, may be the key man in Tuesday's National Basketball Association college draft.

There isn't much doubt about the first three players picked. Barring any last minute trades or sudden changes of heart, the first will be 7-1 Joe Barry Carroll of Purdue by Boston, followed by 6-4 Darrell Griffith of national champion Louisville by Utah and 6-11 Kevin McHale of Minnesota by Golden State.

The Chicago Bulls pick fourth and the consensus around the league is that Lester is the fourth best player in the country -- if he's healthy.

The Bulls want Lester badly, but his knee apparently is scaring them away.

He injured it twice last season, had ann operation, then injured it again.

Doctors in Chicago, Philadelphia and Denver have examined Lester's knee in the past couple of weeks, but their findings are inconclusive.

Lester's knee is strong and there is no apparent structural damage, but he will not consent to an arthroscopic examination, a procedure by which doctors can look into the knee joint. That has a number of teams, particularly Chicago, leery about picking him high in the draft.

If Lester's knee scares the Bulls away, it will affect the rest of the first round. If they take a chance and pick him, the first 10 or 11 picks should fall right into line.

Denver, picking fifth, is expected to take guard Kelvin Ransey of Ohio State; New Jersey, picking sixth and seventh, will probably choose Mike O'Koren of North Carolina and Mike Ginski of Duke; Philadelphia is expected to use its eight pick to take guard Andrew Toney of Southwest Louisiana; San Diego, picking ninth, will probably select Kiki Vandeweghe of UCLA; Portland, picking 10th, will most likely take forward James Ray of Jacksonville and Dallas, picking 11th, will take either forward Michael Brooks of La Salle, forward Ricky Brown of Mississippi State, or forward Larry Smith of Alcorn State.

If the Bulls don't take Lester, they say they probably will go after Ramsey or Ray or they might even trade the pick.

Lester is perhaps the best all-around guard in college -- if his knee is sound. He's quick, a good defender, and can score if he has to.

Carroll is one of the best centers to come along in a long time. With that position so hard to fill, he is almost certain to be the first player picked. He averaged 22.3 points a game last season and shot 54 percent. He's a good shot blocker, but not a particularly impressive rebounder.

Another rap against Carroll is that he doesn't like to run. Some people also question his desire.

Griffith, the Louisville jumping jack, is a crowd-pleasing, razzle-dazzle type who will be a gate attraction wherever he plays.

McHale is the one player no one has any reservations about.

"You're going to get a full day's work out of him everyday," said Bullet General Manager Bob Ferry. "He's 6-11, a great shooter and he rebounds and hustles. He's an achiever."

Other top prospects are guard Larry Drew of Missouri, forwards Don Collins of Washington State, Mike Woodson of Indiana and Reggie Johnson of Tennessee.

The Celtics obtained the first pick in the draft from Detroit in the deal that sent Bob McAdoo to Detroit and brought M. L. Carr to Boston.They originally wanted to draft 7-4 Virginia freshman Ralph Sampson, but when Sampson turned down their five-year contract, at $750,000 per year, they started thinking about Carroll.

Some NBA sources say the Celtics are leaning toward trading that pick to get both a center and badly needed guard. The deadline for trades prior to the draft is 6 p.m. Monday.

Boston, Denver, New Jersey, Philadelphia and Utah each have two first round picks. Houston, Indiana, Los Angeles, Milwaukee and Phoenix don't have any choices in the first rounds.