Boston Celtics president of basketball operations Danny Ainge said the team has talked with point guard Rajon Rondo about a contract extension, but the restrictive nature of the collective bargaining agreement makes it more likely that talks will escalate after this season.

The Celtics expect Rajon Rondo "will demand quite a bit in the open market," president of basketball operations Danny Ainge said. "The competition for Rondo in free agency will be very high." Kim Klement/USA TODAY Sports

"We did talk to Rondo about extending him," Ainge said Thursday during his weekly appearance on Boston sports radio 98.5 the SportsHub. "But that's all part of the negotiation that will happen again this summer and most likely the summer after."

Later Ainge added, "In the collective bargaining agreement, there are limits on what can and can't be done. Really, it's not that Rondo doesn't want to accept an extension, as much as it's just not financially smart for him to accept it right now. We didn't think he would [sign], but we did try."

Pressed on the potential parameters of an extension, Ainge backed off, noting as he often has that he preferred not to discuss negotiations through the media and admitting, "I think we've said enough."

"I think that Rondo will demand quite a bit in the open market," Ainge said. "The competition for Rondo in free agency will be very high."

Next season will be Rondo's last from his five-year, $55 million extension that he signed in October of 2009. The new CBA limits the length and value of a possible extension at the moment, though the two sides could re-explore that option this summer. However, Rondo's most lucrative offer would come after the 2014-15 season, when he'd hit the open market.

Last week, Rondo returned from a near one-year absence after tearing his ACL. He appeared in three games before sitting out Wednesday's win in Washington as a precaution as he eases his way back.