The contract extension talks that extended longer than some suspected they would finally have come to a conclusion.

The Jazz and point guard Deron Williams will formalize a multiyear extension — guaranteed to be worth about $50 million over three years, and potentially worth nearly $70 million if a fourth-year player option is exercised — with a news conference this afternoon.

"There's going to be a great announcement ... in Salt Lake City," Williams' Houston-based agent, Bob McClaren, said via cell phone Thursday afternoon. "One that will make everyone happy, I think."

Later Thursday, the Jazz called a press conference for 2 p.m. today regarding Williams, who according to an e-mail from the team "has agreed in principle" to the extension.

The paperwork was not actually signed as of Thursday and the two sides were "still kind of wrapping up the details," McClaren said, but that is expected to be completed by this afternoon.

Williams — who leaves this weekend for Las Vegas, where he will join Team USA in preparation for next month's Summer Olympics in Beijing — very much wanted to get the extension done by today. The No. 3 overall selection from the 2005 NBA Draft took part in the Jazz's Rocky Mountain Revue summer-league practice Thursday morning, but would not speak at length with reporters, saying only, "See y'all tomorrow."

Terms were not released by either side, and Jazz general manager Kevin O'Connor declined to comment when reached late Thursday afternoon.

McClaren also declined to divulge details of the agreement, but did say, "It's a big commitment from both sides and a continuation of a great partnership."

According to a source with knowledge of the deal, the extension matches that agreed to on July 4 by point guard Chris Paul, the No. 4 overall pick in Williams' draft, and the New Orleans Hornets: three years guaranteed, max money, with a fourth-year player option.

That came shortly after the NBA's negotiating period opened July 1.

Talks with Williams took much longer, partly because Williams took a family vacation to Mexico earlier this month.

Williams already is under contract for next season at $5,069,449.

The extension will kick in beginning with the 2009-10 season and would run through the 2012-13 season if the extra-year option is exercised.

A max-money contract, based on a projected $60 million team payroll salary cap for 2009-10, would start at $15 million per season for Williams — 25 percent of the cap, the most allowed based on his years of NBA service — and would come with incremental 10.5 percent pay raises each year.