Minnesota.Twins.MLB.com

By Mark Sheldon / MLB.com

Joe Nathan finished the 2003 season with a 12-4 record in 78 appearances with the Giants. (Ed Andrieski/AP)

MINNEAPOLIS --- The temperature of the Twins' hot stove season just climbed from space heater to something more like a blast furnace.

Minnesota traded catcher A.J. Pierzynski to the Giants on Friday for relief pitcher Joe Nathan and two minor league pitchers.

Twins general manager Terry Ryan phoned Pierzynski, who was in Hawaii for vacation when he received the news.

"I'm shocked and excited," Pierzynski said. "You're always a little disappointed and sad (to be traded)."

The 26-year-old Pierzynski, a 2002 All-Star, established career highs in 2003 by batting .312 with 11 home runs and 74 RBIs. He is also considered one of the top defensive catchers in the game.

"We had depth at catching," Ryan said. "It's one of the strongest areas in our system. It allowed us to free up some dollars and get some pitching."

Pierzynski's departure clears the way to promote top prospect and 2001's overall No. 1 draft pick, Joe Mauer. The 20-year-old St. Paul native batted a combined .339 with five homers and 85 RBIs this season with Single-A Fort Myers and Double-A New Britain and was named Minor League Player of the Year by Baseball America.

The Twins had a $55 million payroll for 2003 and said it would remain about the same for 2004. However, the club is trying to retain free agent relievers Eddie Guardado and LaTroy Hawkins along with outfielder Shannon Stewart. The club is also likely to absorb additional salary increases due to arbitration.

Pierzynski earned $365,000 this season but was one of five players eligible to earn a substantial raise through arbitration. First baseman Doug Mientkiewicz, second baseman Luis Rivas and pitchers Johan Santana and J.C. Romero remain eligible.

Fitting everyone into the budget could mean that more tough decisions are coming.

"We've got a lot of challenges ahead and a lot we're trying to accomplish," Ryan said. "It could be a very active winter for us. ... we're in a tough economic situation."

Nathan, a right-handed setup man, led all Major League relievers in wins this season with a 12-4 record and 2.96 ERA in 78 appearances for the NL West Champion Giants.

"He's got a good arm and gets people out," Ryan said. "He had a good year with the Giants and he's playoff tested."

A first-round pick by San Francisco in 1995, Nathan will turn 29 next Saturday. He began his Major League career as a starter in 1999. But a shoulder injury and surgery forced him to miss the entire 2001 season and spend most of 2002 in the minors. Now fully healed, he features four pitches with a fastball in the mid-90s

"He's a stud," Twins manager Ron Gardenhire said. "Everything I've heard is he's a horse with a great arm. He should be a big part of our bullpen."

Nathan could not be reached for comment. He will be eligible for arbitration for the first time after the 2004 season.

The Twins also received Triple-A starter Boof Bonser and Single-A pitcher Francisco Liriano. They will also send the Giants either cash or a player to be named later to complete the deal

Bonser was 8-12 with a 3.83 ERA 28 starts for Double-A Norwich and Triple-A Fresno. He was the Giants first-round selection in the 2000 draft. Ryan is considering adding the 22-year-old to the club's 40-man roster.

"He's a young right-handed pitcher with a good arm and good stuff," Ryan said. "We think he's got the strength and stamina to be a future starter in the big leagues."

Liriano, a lefty, was 0-2 with an 8.00 ERA while allowing 10 hits with eight walks and nine strikeouts in five starts Arizona League Giants and Single-A San Jose. The 20-year-old was limited to just five games in 2003 due to a shoulder injury.

"The left-hander has an excellent arm," Ryan said. "We've got a good look at him in the instructional league and we liked what we saw."

Pierzynski was the Twins' third-round pick in 1994, with his debut coming in the 1998 season. He didn't become a regular fixture in the lineup until 2001 and has a career .301 batting average. He is still trying to get used to the idea that he will be playing in a new uniform next year.

"It hasn't sunk in yet because it's not like I have to play a game tomorrow," Pierzynski said. "It's cool that someone wants you, but it's tough."

"When you have a player that has roots in our organization like A.J., it's a little different than someone who was here for a year or so," Ryan said. "He had a lot of history and a lot of success. We picked him out of high school. We got to know his family."

The trade also brought mixed emotions to others in the Twins organization.

"I like him. He did just about anything you could to get a win," starting pitcher Kyle Lohse said. "He called a great game for me. It's kind of sad. It makes you wonder who else they'll keep and who they won't try to sign. It'll be pretty interesting."

"We lost a pretty good player," third baseman Corey Koskie said. "He caught every day. There's not much more you can ask than that. It's something you have to deal with. It's a business, that's the bottom line. Players like playing in one spot, but the chances of that aren't good in a situation like this."

Gardenhire said he was sad to see Pierzynski go. But, he said wasn't concerned about the possible changes that could affect his roster in the weeks ahead.

"We're going to have a good baseball team," Gardenhire said.

Mark Sheldon is a reporter for MLB.com. This report was not subject to the approval by Major League Baseball or its clubs.