SAN DIEGO – The trade of All-Star slugger Adrian Gonzalez from his hometown San Diego Padres to the Boston Red Sox is all but finalized, two people with knowledge of the situation told The Associated Press on Sunday night.

The people spoke on condition of anonymity because the trade hasn’t been announced. The Red Sox, however, called a news conference for this morning.

The deal appeared to be in jeopardy when Sunday afternoon’s deadline passed without the Red Sox and the first baseman agreeing to a contract extension.

However, the sides are believed to have agreed to continue to talk in good faith toward an extension.

The other person said a few technicalities need to be finished. It’s believed the three prospects heading to the Padres must still pass physical exams.

The Padres, who have a long history of dumping star players because of financial reasons, will receive minor league right-hander Casey Kelly, first baseman Anthony Rizzo and outfielder Reymond Fuentes, plus a player to be determined later. Kelly and Rizzo played with the Portland Sea Dogs last season. Gonzalez played with the Sea Dogs in 2001.

Because of the caliber of the prospects they’re giving up, the Red Sox wanted to protect themselves by extending Gonzalez’s contract beyond 2011. Although the sides couldn’t agree by the 2 p.m. deadline Sunday, it’s thought the sides exchanged parameters and will continue to work toward a deal.

Agent John Boggs has said in recent interviews that Gonzalez wants fair market value.

It’s believed that if Gonzalez were to hit the free agent market, he’d command a contract similar to that of Mark Teixeira, who finished the second season of a $180 million, eight-year contract with the New York Yankees.

Padres General Manager Jed Hoyer — who used to work in Boston’s front office — has said for some time that the Padres wouldn’t be able to afford the kind of big-money contract Gonzalez would command if he hit the free-agent market.

The Padres recently exercised Gonzalez’s $6.2 million option for 2011, the final year of a team-friendly $15 million, five-year contract he signed in 2007.

The left-hander hit .298 with 31 homers and 101 RBI last season. In five seasons with San Diego, Gonzalez has 161 homers and 501 RBI. Including parts of two seasons with Texas, he has 168 homers and 525 RBI.

He set a Padres record with his fourth 30-homer season.

Gonzalez had surgery to clean up the labrum in his non-throwing right shoulder on Oct. 20.