MIAMI -- Barring any setbacks, Emilio Bonifacio is expected to begin a rehab assignment with Class A Jupiter on Wednesday.

Bonifacio, on the disabled list with a sprained left thumb, remains optimistic that he will be reinstated on Aug. 19, in time for the finale of a four-game set at Colorado.

Since Friday, he's been testing the thumb while hitting off a tee. He was back in the cages on Sunday, taking swings and saying his thumb was progressing nicely.

Bonifacio reinjured his thumb in the second game of a doubleheader at Washington on Aug. 4.

Initially, the club feared the worst. The belief was Bonifacio had done serious damage to the thumb and he would be lost for the season.

But an MRI showed no structural damage.

Bonifacio had surgery to repair a torn ligament on May 25. Two pins were inserted to stabilize the thumb.

When he returns, the question will be where he will play.

After opening the season in center field, Bonifacio was moved to second after Omar Infante was traded to the Tigers on July 23.

Because Bonifacio has injured the thumb twice already, manager Ozzie Guillen feels center field could be his safest position. But one reason the club traded Infante was because it felt Bonifacio was a natural replacement.

At second base, there are more chances of injuring the thumb. The position requires more diving, as well as applying tags.

Bonifacio says he is fine at either position.

"When I get back, if they put me at second, I'm not going to be like half [healthy]," he said. "I'm going to be 100 percent. But like Ozzie says, you've got more chances [to get hurt] at second. I don't care where they put me. I don't have a problem with where they put me."

New surroundings agree with Lee

MIAMI -- A change of scenery has picked up Carlos Lee's production, especially his RBI totals.

When the Marlins acquired Lee from the Astros on July 4, they were hoping to pair him in the middle of their order with Giancarlo Stanton.

It didn't exactly work out that way, as four days later, Stanton underwent surgery on his right knee and missed a month.

Lee didn't replace Stanton's home run totals, but the 36-year-old first baseman has done his part driving in runs.

In his first 33 games with the Marlins, Lee drove in 25 runs. He added a crucial two-run double on Saturday night in Miami's 7-3 win over the Dodgers at Marlins Park.

Driving in runs was a challenge for him in Houston, mainly because he didn't have as many chances as he has now.

In 66 games with the Astros before he was dealt to Miami, Lee knocked in 29 runs in 66 games.

"Carlos is an RBI machine," manager Ozzie Guillen said. "That's the reason he's made a lot of money over his career. Even as a kid, when I had him with the White Sox, [I liked] his approach and he learned how to do it [better], it's a lot better [now]."

Guillen managed Lee when they were both with the White Sox in 2004.

Lee's batting average pretty much is the same in Miami as it was in Houston. With the Astros, he was hitting .287 at the time of the trade. In Miami, his average is .289.

In his last 16 games, Lee has 16 RBIs.

"He doesn't panic when we have people on base," Guillen said. "He's got a little bit of an idea of what they want to do to him, and if you put it all together, you're always going to hit with men on base. You don't change your approach."

August has been kind to Buck

MIAMI -- The first four months of the season weren't kind to John Buck. However, the first two weeks of August have been a different story.

The Marlins' catcher has struggled offensively for most of the season, hitting .168 with a .287 on-base percentage and a .295 slugging percentage through the end of July. Since the calendar turned to August, though, Buck has turned things around at the plate.

"He's swinging the bat a little bit better the last two weeks," Marlins manager Ozzie Guillen said. "Even though you look up and his average is still low, the last couple weeks he's swinging the bat better."

Although his season average is still not where he'd like it to be -- .186 entering play on Sunday -- Buck is hitting .333 (10-for-30) and slugging .567 in August. Of his 10 hits this month, seven have been doubles, including a game-tying two-bagger in Saturday's 7-3 win against the Dodgers. The seven doubles are as many as he had during the first four months.

"I feel good," Buck said. "The ball is hitting my bat and going where it needs to go, instead of at people. I'm also not missing my pitches."

Buck credited much his recent turnaround to Marlins hitting coach Eduardo Perez, who has put in extra work with the backstop. Perez noticed on film that Buck was just missing pitches earlier in the season and suggested the former All-Star drop his hands a few inches in his approach. So far, the adjustment has paid off.

"He's [gotten] big hits for us; I hope he keeps it up," Guillen said. "We've got a lot of baseball games to go, and [we've] got a chance to make a pretty good comeback."