Everything appeared to be set, the deal to get Coach Doc Rivers to the Clippers from the Boston Celtics just a formality once the NBA opened its offices Monday.

But there have been obstacles that prevented the on-again, off-again deal from being completed, leaving it to be approved by the NBA another day.

The Clippers were trying to work out details and the language of Rivers' contract so it can be finalized, something that the team expects to happen by Tuesday.

The Clippers had not submitted the contract to the NBA because it wasn't complete. The Clippers worked all day Monday trying to finish the complicated deal.

Details of how all this has been happening were told to The Times by NBA executives who were not authorized to speak publicly about the ongoing situation.

"This is not out of the ordinary," one executive said. "It's normal contract details."

The Clippers and Celtics agreed in principle Sunday for Rivers to come to L.A. and for the Clippers to send Boston a first-round draft pick in 2015. The pick will not be lottery-protected.

The Clippers and Rivers agreed that L.A. would take on what was left of Rivers' contract with the Celtics.

He had three years left on his deal for $21 million. That's what Rivers will earn with the Clippers, said the NBA executives.

Clippers owner Donald Sterling, a notorious frugal spender, had agreed to make Rivers the highest-paid coach in franchise history, the executives said.

The Clippers are hoping to have a news conference Wednesday to announce that Rivers, 51, is their new coach who will replace Vinny Del Negro.

The Celtics had called a news conference for Monday at their practice facility, but it was canceled and there was no timetable for it to be rescheduled.