BOSTON -- As manager Jim Leyland promised, some of the Tigers were on the field at Fenway Park early on Wednesday afternoon for some extra work. It didn't all have to do with the struggling offense, though.

Carlos Guillen hasn't been slumping at the plate, but his defensive footwork had somehow gotten into a slump. So infield coach Rafael Belliard took Guillen out to the field early and drilled him on the proper stance to have at the bag when readying for a throw.

It's not simply a matter of allowing him to field throws better. It's a matter of allowing him to avoid a collision with a baserunner.

"The way he was doing it, he could get hit and get hurt," Belliard said. "He was in the running lane a lot of times."

Added Leyland: "We don't know how it started, but we hope we put an end to it today."

The trend developed last week, and it happened at least a few times over the course of last weekend's series with the White Sox at Comerica Park. Belliard noticed it once during the season-opening series against the Royals, but neither he nor Leyland saw it at all during Guillen's time at first base last season or in Spring Training last month.

Thus, it's not that Guillen is struggling to handle the adjustment to first base. It's that he fell into a bad habit.

"You have to have good footwork," Belliard said. "The ball is going to tell you how to go. The throw, you have to see the ball before you commit how to go. That's what we worked on, to get out with the ball, go at the same time as the ball."

Belliard worked with Guillen on planting his right toes on the bag while using his left foot to stretch out with his glove side.

"If you throw your left foot to the ball, it's easy," Belliard said.

So Belliard had Guillen working on his foot plant while taking throws from third baseman Miguel Cabrera, who was at the park for early work on his hitting.

Once they have that down, Belliard believes, Guillen should be all right.

"First base is not that easy," Belliard said. "You have to be a good athlete. I think when you go from short to first base, it's easier for any position guy going from there. A lot of things happen at first base, just like a lot of things happen at shortstop."