© 2010 MLB Advanced Media, L.P. All rights reserved.

06/16/10 4:10 PM ET

Pirates promote top prospect Alvarez

Infielder Iwamura designated for assignment

PITTSBURGH -- Amid anticipation not seen since Barry Bonds arrived in Pittsburgh in 1986, Pedro Alvarez will make his Major League debut tonight at PNC Park.

The Pirates have played their first 64 games this season amid speculation as to when the slugging third baseman would arrive. Now, Pittsburghers who have imagined Alvarez's left-handed bat in PNC Park since the third baseman was drafted No. 2 overall in 2008 have to wait no more.

To make room for Alvarez, the Pirates designated infielder Akinori Iwamura for assignment.

Alvarez, the organization's top Minor League prospect, left his Triple-A teammates after their loss in Scranton Wilkes-Barre (Pa.) to head this way. Indianapolis manager Frank Kremblas delivered the news to Alvarez, who then shared it with family members who were in town to watch him play.

Pirates manager John Russell is expected to slot Alvarez right into the middle of a lineup that has been starved for both production and power recently. The Pirates rank last in the Majors with 204 runs scored, and only one National League club (the Astros) has hit fewer home runs.

Heading into Tuesday, Alvarez ranked third in the International League in RBIs (53), fourth in home runs (13), third in total bases (129), third in runs scored (41) and sixth in slugging percentage (.540).

"We've envisioned this for the organization," Russell said. "He's done some great things. We'll continue that process. I think he's going to be a big boost for our club."

Though Alvarez ended his Triple-A stint with just two hits in his final 18 at-bats, he finished with a .327 average, two doubles, two triples, five homers and eight RBIs in June. After struggling in April, Alvarez began showing that he could have consistent success hitting off left-handed pitchers. That was something the organization said it would require of him before considering a promotion.

Alvarez won't have to wait for his first test, either, as left-hander John Danks is scheduled to start for the White Sox on Wednesday.

As word of Alvarez's imminent arrival began to trickle through the Pirates' clubhouse Tuesday night, the sting of a nine-game losing streak was at least partially replaced by a palpable enthusiasm and anticipation.

"He's that guy that when he comes up to bat, any time possible he can hit a home run," Andrew McCutchen said. "He's that bat that we're looking for. He's going to help this lineup out a lot. We can't wait for him to get here."

Added Neil Walker: "He's a tremendous talent. I don't think it's fair to say he's going to come here and be hitting home runs every game and driving in a bunch of runs, because that's the type of pressure you don't want to put on anybody. But I think he's going to handle himself tremendously.

"He's prepared himself well since Spring Training. From seeing him in Triple-A when I left, he was hitting the ball hard almost every single at-bat and playing really good defense. I'm sure that's going to carry over."

When Alvarez arrives, he will be the fourth prospect the Pirates have called up in the past three weeks. Walker was the first to arrive and has since cemented a job as the team's starting second baseman. Starter Brad Lincoln and outfielder Jose Tabata joined the team last Wednesday. Tabata is now the club's everyday left fielder, and Lincoln has jumped into the rotation.

Alvarez, general manager Neal Huntington confirmed, will step in as the team's everyday third baseman immediately. There are still questions about whether he can stick there for the duration of what is expected to be a lengthy career, but he'll be given the chance to prove himself.

This means that Andy LaRoche, who has just three hits in his past 29 at-bats, is about to be thrust into a utility role. He took groundballs at second base again on Tuesday, and is expected to dabble defensively around the diamond in the coming weeks.

"Andy has done everything you could ask a teammate to do," Huntington said. "At this point in time, Neil [Walker] has deserved the opportunity to stay out there [at second base]. Andy LaRoche has to be ready to go whether it's as a pinch hitter, it's a spot start at third, it's a spot start at second. Andy is going to capitalize on his opportunities."

The Pirates will have to make a corresponding roster move to clear a space for Alvarez on the 25-man roster. Huntington said that would be done on Wednesday. He did not specify whether a position player or pitcher would be coming off.

Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.