Eager to begin his latest coaching comeback, Pat Rileyarrived for work Monday at 8 a.m. and was surprised to find the Miami Heat offices deserted.

"I didn't realize it was Presidents' Day," he said.

Ah, the old tunnel vision is still there, and Riley hopes to use it to lead a second-half surge by the NBA's defending champions.

He was back on the practice court Monday evening, nearly seven weeks after he stepped down for operations to replace his left hip and repair cartilage in his right knee. Riley led the Heat through a two-hour workout, their first since the all-star break.

"It was good to have him back," C Alonzo Mourningsaid. "It was basically like he hadn't left at all."

He stepped down Jan. 3, and now acknowledges the decision wasn't all about his health. At the time, Miami was 13-17.

"I was not responding very well to the situation," Riley said. "I was very intolerant of just about anything. I don't think I was doing a credible job at all as a coach."

Riley returns with his team at .500 and on the rise. With Shaquille O'Nealhealthy and Dwyane Wadein top form, the Heat have won seven of their last eight games to reach 26-26, their best record since they were 3-3.

Miami opens the second half today in Houston, followed by an NBA Finals rematch the next night at Dallas.

· CELTICS' RAY ASSIGNED:Boston has assigned rookie G Allan Rayto the NBA Development League's Austin Toros, the team announced.

Ray has appeared in 33 games for the Celtics this season, averaging 4.9 points and 1.1 rebounds in 10.6 minutes. The Celtics signed Ray in July as an undrafted free agent from Villanova.

-- From News Services