By Gary Washburn, Globe Staff

Team president of basketball operations Danny Ainge was coy this morning when asked about Terrence Williams' contract, telling the Globe "we're still negotiating" with a wry smile.

The Celtics were indeed negotiating with Williams' representatives on a deal not only for the remainder of this season but a conditional deal for 2013-14, according to an NBA source. Williams has played three games for the Celtics entering tonight's game against the Golden State Warriors but has impressed with his ability to play point guard.

The club had until tonight to sign Williams to another 10-day contract but chose to lock up the former lottery pick to an extended deal. Williams has blended in well with his teammates and Doc Rivers told reporters Thursday that Williams is a natural point guard, a position the Celtics need desperate help at after the season-ending injury to Rajon Rondo.

Williams played in China this season after spending training camp with the Detroit Pistons. He played with the New Jersey Nets, Houston Rockets and Sacramento Kings but picked up a reputation of being difficult to coach before being waived by the Pistons in training camp.

Williams is the first of three players signed from the Chinese Basketball Association along with D.J. White and Shavlik Randolph.