As old-timer races go, this one is rare. Kevin Garnett, whose 13-rebound performance against Golden State Friday moved him past Hakeem Olajuwon into 11th place on the NBA’s all-time rebounding list, leapfrogged into 10th place with 10 rebounds against the Pacers last night. This time he passed Wes Unseld. These are big names, as the Celtics center is well aware. “Oh, man, you serious?” Garnett said with a slightly disbelieving laugh when informed of the legends he has passed. “Yeah, those are huge names, players I look up to. I’m kind of lost for words. I’m flattered. Hard work does pay off.” Garnett now has 13,774 career rebounds. Ninth place, held by Walt Bellamy with 14,241 boards, would be a bit more of a leap. A seed planted As further evidence of the season’s improbability, the Celtics’ 83-81 win found them 11⁄2 games out of the Eastern Conference’s fourth playoff seed — the spot currently held by Brooklyn (35-26). The Celtics (33-27) actually gained a game on Chicago (34-27), which lost to San Antonio. Though Doc Rivers and his veterans prefer not to pay heed to these numbers, even the Celtics coach had to admit that his team has a chance at far more than anyone deemed possible. “It’s definitely more important to be right (physically),” he said. “If you’re injured and not right then it doesn’t matter what seed you are. You’re going home soon.