WALTHAM, Mass. - Kevin Garnett isn't ready to start the playoffs, and Boston Celtics coach Doc Rivers said Thursday that there's a strong possibility that he will miss the entire postseason.

"He's not going to be ready. After watching him practice, there's no way," Rivers said on WEEI-AM. "The way I saw him move today, I don't know if he'll be ready."

When asked to clarify, Rivers said there was a chance Garnett could be out for the rest of the season. Celtics spokesman Jeff Twiss said he could not elaborate on Rivers' comments.

The Celtics begin the best-of-seven first round series against the Chicago Bulls on Saturday.

"We're going to move on without him," Rivers said.

Garnett has been the Celtics' inspirational leader since joining them in a 2007 trade that completed the new Big Three and propelled the franchise to its record 17th NBA title. He averaged 15.8 and 8.5 rebounds per game for the defending champions this season.

He injured his right knee Feb. 19 and missed the next 13 games before returning for four, but never playing as many as 18 minutes. With the Celtics assured of a high playoff berth, Rivers then held Garnett out with an eye toward bringing him back for the last three games of the regular season; that became the last two, then the last one, but he never made it back.

Rivers said Thursday he watched Garnett run at the team's practice facility and said he had to shut him down after 20 minutes.

"If he can't get through biking and working out without swelling and his leg locking, I don't know how you can play in the playoffs," Rivers said. "This was an honest run today, you couldn't make your way through it. The guy's a warrior, you see him try to mask his way through it. But after 20 minutes of running, I don't see it. After today, there's no way he can play."

Garnett's reaction?

"He was frustrated. He was mad at me, mad at everybody. Then he understood," Rivers said. "He put up a fight. He's really frustrated, but that's Kevin. That's why we got him, because he cares so much."

Celtics owner Wyc Grousbeck said he's confident Garnett is going to be "absolutely fine, 100 percent, over the long term. The short term is much less clear at this point."

Boston was 18-7 without Garnett this year and finished the season 62-20 _ not good enough to secure the home-court advantage that proved crucial in last year's title run. Should the Celtics meet the Cavaliers in the Eastern Conference finals, they would open the series in Cleveland; the Los Angeles Lakers would also have home-court in a potential NBA finals matchup.

But, without Garnett, what had seemed like an easy road through the early rounds has gotten more difficult.

A service of the Associated Press(AP)