The Sonics' first full day of training camp started with an unfortunate twist when Nick Collison injured his shoulder yesterday morning.

Just how unfortunate that turns out to be was being evaluated last night. Collison missed the evening practice to have a magnetic-resonance image taken. Results were expected this morning.

Collison, the team's top draft choice at No. 12 in June, injured his shoulder during a four-on-four scrimmage.

It was the first workout in which all team members were present, although Collison and players with fewer than four seasons of NBA experience had been practicing since Saturday.

Depending on the severity of the injury, it could put Collison next to fellow first-round pick Luke Ridnour in the first-aid line, deflating some of the excitement over the team's first pair of first-rounders since 1989.

Ridnour has been held out of most drills as he recovers from abdominal surgery. He hurt an abdominal muscle in a workout in May, and it kept him out of the Sonics' summer league in July. He underwent surgery the first week of August, and this week has taken part only in drills in which he is unguarded. Coach Nate McMillan said he doesn't expect Ridnour to start full practice until mid-October.

McMillan said he didn't know how Collison was injured. Teammate Rashard Lewis said he thought Collison was hurt reaching for a loose ball.