JUPITER, Fla. -- Nothing is official, but if recent days are revealing anything, the Marlins' initial four-man rotation is starting to take shape.

What is known is that Mark Hendrickson will pitch in the March 31 season opener against the Mets, who are countering with Johan Santana. And Scott Olsen will take the mound on April 4, in the fourth game when the Pirates are at Dolphin Stadium.

Still unannounced are the second and third starters.

Yet, the way things are lining up the rest of Spring Training, Rick VandenHurk would go in the second game of the season and Andrew Miller would start in the series finale on April 2 against the Mets.

In that scenario, Ricky Nolasco projects to make the team as a long reliever and would become the fifth starter on April 13 at Houston. The Marlins have two early off-days, and they plan on going with a four-man rotation until that day.

These projections are based on how the starting pitching is falling into place.

The Marlins also plan to keep giving a long look at their No. 1 prospect, 21-year-old Chris Volstad.

A first-round pick in the 2005 First-Year Player Draft, Volstad entered Spring Training on a roll. The 6-foot-7 right-hander had given up just two runs in 16 innings. But on Monday, he struggled with his command. His pitches elevated, and the Astros hit him hard, scoring seven times in two innings off him.

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"It was just one of those days for him," manager Fredi Gonzalez said. "That's why you don't panic. Everyone is allowed to have one of those in Spring Training, and his came today. We'll just go forward."

Volstad remains in line to face the Yankees on Saturday night in the Marlins' final Spring Training game. It will be played at Dolphin Stadium, and an estimated 30,000 will be on hand.

For Volstad, a resident of Palm Beach Gardens, Fla., every day he remains in big league camp is a bonus.

"I guess I really didn't see myself being here [a week] before Opening Day," he said. "This was really more than I could really hope for. I was just trying to go out here and stay as long as I could."

If Volstad opens the season at Double-A Carolina, which is likely, he would be given more time to develop into the type of pitcher so many in the organization believe he will become.

Volstad has 385 2/3 innings of Minor League experience, including 42 2/3 last year at Double-A.

"I definitely feel closer," Volstad said of being big league-ready. "I feel like I gained a lot last year in Double-A, and even this spring, I feel like that I've made progress, and that I'm closer than ever."

The rest of the pitching staff also is falling into place. Doug Waechter and Joe Nelson, who both have Minor League deals, project to open the season at Triple-A Albuquerque.

The Marlins plan on carrying 12 pitchers, including eight relievers the first two weeks.

Gonzalez said he is leaning toward carrying the fifth starter as a reliever until April 13.

The bullpen most likely shapes up as including Kevin Gregg, Justin Miller, Taylor Tankersley, Matt Lindstrom, Lee Gardner, Renyel Pinto, Logan Kensing and Nolasco until he gets slotted into the rotation.