About the challenge to establish definitive roles as soon as possible for new acquisitions Tony Delk and Rodney Rogers? For Celtics coach Jim O'Brien, it turns out there was no challenge in the process at all.

``Tony Delk is going to start, so much for that challenge,'' O'Brien said after practice yesterday at The Sports Authority Center in Waltham. ``Rodney has to be able to play the (power forward) spot, where there's not going to be a lot of minutes - about 8-10 minutes a game to free up Antoine (Walker) to play 38-40 minutes.

``But (Rogers) has got to learn the (small forward) spot and the (center) spot, so it's more of a challenge for Rodney. Certainly when he learns to play those spots at a high level, not only offensively but defensively, he'll be able to contribute more.''