After filtering out of Fenway in the dead of night, they arrived at their hotel at 5 a.m. Friday and eight hours later were at Coors Field, checking out the dry, thin air of a ballpark as unique as the one off Kenmore Square.

With no designated hitter in the National League city, Boston will move David Ortiz to first despite a bad knee while regular first baseman Kevin Youkilis is benched and Mike Lowell remains at third. Ortiz played seven times at first this year, all in interleague play. He's not a Hoover.

"Anything around me, it's going to be (caught). After that, I don't know," he said. "I've played first base before and it wasn't that bad. It's just not Gold Glove-caliber."

Daisuke Matsuzaka, Boston's $103 million pitcher, starts against Josh Fogg, who was born in Lynn, Mass., of all places, and is the son of a Red Sox fan.

Players weren't the only ones soaking it all up during Friday's workouts. In a silver-colored contraption under the stands between home plate and first base, next to a huge cooler of Coors Light, 142 dozen baseballs were stored behind a padlock in the moist air of the ballpark's humidor.

Since it was introduced in 2002, Coors has been stripped of its reputation as baseball's best launching pad, with home runs and scoring dropping as steeply as a Rocky Mountain ski trail.

"Balls aren't as hard," Rockies reliever LaTroy Hawkins said. "Not like bricks. They're not hitting rock. They're hitting the same ball as in those other places."

Instead of thinking about Rico Petrocelli or even Doug Mirabelli this weekend, Red Sox fans might be more concerned with Bernoulli - specifically whether Dice-K's curveball will flatten out in the thin air under Bernoulli's Principle, which explains why airplanes fly.

"The amount of pressure difference created by the spin depends directly on the density of the air itself," Bennett Goldberg, chairman of the Boston University College of Arts and Sciences physics department, was quoted as saying on the school's Web site.