Most coaches leave their starters in for the majority of the first half, fine-tuning the offense and defense in preparation for the season opener.
Here's what we're watching for in Friday's games:
We've been down this road with Stevan Ridley before. Is he back in Bill Belichick's doghouse after last week's red-zone fumble? Keep an eye, too, on the Patriots receivers. Julian Edelman and Kenbrell Thompkins were the starters last week, with Danny Amendola and Brandon LaFell in the third and fourth roles.
The Raiders' first-team offense has struggled mightily, in large part due to Matt Schaub's inability to power throws outside the numbers and down the seam. He's gotten little help from his offensive line or wide receivers, but his arm still looks shot. Will he continue to be outplayed by third-stringer Matt McGloin? If so, will the coaching staff be tempted to make an unexpected change in September?
So why is Robert Turbin still ahead of him in the backfield pecking order? As gifted as Michael is, he hasn't stood out in preseason action the past two weeks.