MIAMI -- Miami Dolphins running back Daniel Thomas sat out practice for the second day in a row Thursday because of a concussion, increasing the likelihood Lamar Miller will make his NFL debut Sunday against the Oakland Raiders.
Thomas, the backup to starter Reggie Bush, was hurt in the second quarter of last week's season-opening loss to the Houston Texans.
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Miller traveled with the team but was inactive. He ran for 1,272 yards last year for the Miami Hurricanes, and the Miami native said he looks forward to returning to Sun Life Stadium, this time as a pro.
"It's a great feeling," he said. "I've been playing there for three years. It's just a blessing. A lot of people don't get this opportunity. I'm just trying to take full advantage."
Also missing practice were receiver Anthony Armstrong (hamstring) and defensive tackle Tony McDaniel (knee).
The Dolphins are looking for more productivity from their No. 2 running back. As a rookie last year, Thomas averaged only 3.5 yards per carry in that role, and didn't score in 165 attempts.
Miller averaged 5.7 yards per carry with the Hurricanes and scored 17 touchdowns in 23 games. He was drafted in the fourth round by the Dolphins.
"Obviously Lamar Miller we drafted for a reason," coach Joe Philbin said. "We think highly of him. We think he's going to be a good player in this league."
Miller said Bush, a 1,000-yard rusher last year, has been a helpful mentor.
"He has taken me under his wings," Miller said. "Reggie has been helping me a lot with pass protection and the playbook and studying my opponents."
Miller was the team's busiest running back during the exhibition season. He rushed for 91 yards in 30 carries and caught seven passes for 56 yards.
He said he's ready for a chance in a game that counts, and Bush agreed.
"I think it's time," Bush said. "If he gets his shot he'll do fine."
Regardless of who carries, the Dolphins hope to run the ball more than last week. They averaged 4.2 yards per carry against Houston but abandoned the ground game after falling behind 24-3 in the first half.