BRADENTON, Fla. — Left-hander Sean Burnett and right-hander John Van Benschoten, two of the Pittsburgh Pirates' top pitching prospects, returned to the mound Wednesday for the first time since missing last season with arm injuries.

Both pitchers threw for several minutes in the bullpen on the first day of workouts at the Pirates' midwinter pitching minicamp, and both are on pace for spring training.

"It's a good thing to see," manager Jim Tracy said. "You want to be cautious about where they are, not push too hard, let them work at their own pace, but you like to see them out there throwing a baseball."

Burnett, the team's 2000 first-round draft pick, had reconstructive left elbow surgery after going 5-5 with a 5.02 ERA and a five-game winning streak in 2004. He resumed throwing early this winter.

"It felt great," Burnett said. "You do all that rehab, all that time in the training room, it's good to see the work pay off. I thought I was throwing well and throwing for strikes. That was the key."

The Pirates originally projected Burnett would not be available until June, so they are encouraged he has been pain-free for six weeks. If he stays that way, he could compete in spring training with right-handers Ryan Vogelsong, Ian Snell and Victor Santos for the No. 5 spot in the rotation.

"Is he a candidate to have an opportunity to make the club? I don't know the answer to that," Tracy said. "We'll take it a day at a time and see how he progresses from a health standpoint. If he comes along quicker, that obviously creates more options for us."

The top four starters are expected to be left-handers Oliver Perez, Zach Duke and Paul Maholm and right-hander Kip Wells.

Van Benschoten, a 25-year-old right-hander, also made his debut in 2004 by going 1-3 with a 6.91 ERA in five starts. He sat out last season after needing surgery on both shoulders to repair labrum tears.

Even if healthy, the 2001 first-round draft pick likely will open the season at Triple-A Indianapolis.

"It was just good to be in the drills and participating instead of watching everybody," Van Benschoten said. "You feel part of something again."

The Pirates also got an upbeat medical report from outfielder Chris Duffy, who has had no complications since tearing his left hamstring in September. Duffy, the projected starting center fielder and leadoff hitter, hit .341 in 39 games as a rookie last season.

Outfielder Jody Gerut, limited to 18 at-bats after being acquired in July from the Chicago Cubs, said his right knee is fine following major knee surgery in September 2004. For the first time since he joined the Pirates, he worked out Wednesday without a brace.

Second baseman Jose Castillo, who missed the final six weeks of last season because of torn left knee ligament, did not attend the first day of the voluntary minicamp. General manager Dave Littlefield said he was expected later in the week.

Jose Bautista, the organization's top prospect at third base, has a slight fracture in his left wrist and needs four weeks of rehabilitation.