SEATTLE (AP) – Boston coach Doc Rivers thinks the Celtics are at a competitive disadvantage because they’re the only team that will play consecutive nights with the NBA’s new and old balls.

The Celtics faced Seattle on Sunday night with the new synthetic-cover ball and will play in Portland today with the old leather ball. Boston officials even called the league to complain that the Trail Blazers will have the advantage because they have practiced with the old ball. “My assumption is, that (no response) is their answer,” Rivers said.

Players criticized the performance of Spalding’s microfiber composite ball from the moment training camps opened. The NBA stood by the product, but players’ complaints that it cut their skin followed by the filing of an unfair labor practice charge forced commissioner David Stern to put the new balls back on the rack, starting Monday.

Rivers said Sunday that he just wanted the league to delay the change one day, specifically for the Blazers and Celtics.

“I just think it’s unfair that Portland practiced (Sunday) with the new ball and probably will have a shootaround (Monday) with it,” he said. “We’re playing tonight (Sunday) and traditionally teams don’t have shootarounds after back-to-backs. So we won’t see the ball until 5 p.m.

“I would think it would be a smart thing for the league to do is wait one day. I guess they don’t think it’s that smart. The ball is no big deal, but it does give Portland an advantage. They get to work with it.”

AP-ES-12-31-06 2211EST