Hayden suffered a slight hamstring pull in training camp on Monday but Oakland coach Dennis Allen said the decision to hold the rookie cornerback out was related to Hayden's recovery from offseason abdominal surgery.
"We'll see where he's at when we come back to work Wednesday," Allen said. "It's more of a relation to the surgery that he had this offseason as opposed to the heart condition."
Hayden was rushed into surgery last November for a tear of the inferior vena cava, the large vein that carries blood from the lower half of the body to the heart, after a collision in practice. Doctors had to cut through Hayden's sternum to save him. The injury is 95 percent fatal.
The 23-year-old had his offseason cut short when he underwent surgery in late May to remove scar tissue from his abdominal region.
Hayden wasn't available after practice and players were excused from evening meetings. They do not have to check back in until an 11 p.m. curfew on Tuesday.
"We'll kind of re-evaluate (Hayden) after that," Allen said.
The 12th overall pick in this year's draft, Hayden has practiced every day but has been wearing a red jersey normally reserved for quarterbacks and kickers because he has not been cleared for contact yet.
During a team scrimmage portion of practice, Hayden collided with a wide receiver in the end zone then jogged off the field. He pulled up later in practice during a drill pairing cornerbacks against receivers and immediately clutched at his leg.
Although he returned to finish the workout, the Raiders are still being cautious with their first-rounder. Allen said Hayden would not have played against Dallas regardless of what happened in practice.
All the injuries have opened the door for some of the Raiders rookies and newcomers to get an extended look against Dallas.
"It's huge for a number of young guys to get into these preseason games," Allen said. "This is where you really prove that you're worthy of a spot on this roster. This month, at the end of the day, will make or break a lot of these guys."
Allen has not decided on the quarterback rotation against Dallas, though Matt Flynn is likely to start. ... Denarius Moore, the favorite to be Oakland's No. 1 receiver, caught a deep touchdown pass from quarterback Matt Flynn and dropping two passes in a short span earlier in practice. ... Two-time Super Bowl-winning coach Tom Flores attended practice, as did former Raiders Tony Stewart, Sam Williams and Justin Fargas.