MANKATO -- Coach Leslie Frazier said after practice that the goal for right guard Anthony Herrera (knee) is to have him ready to play by the third or fourth preseason game.

"We would like to get him into one of those late preseason games," Frazier said. "Just to see where he is. That' the goal. Whether we can get to that, I don't know. But we'd like to try to get him for that San Diego (season opener). But that will hinge on whether or not we get a chance to see him in the preseason at all."

Herrera, who's on the physically-unable-to-perform list, tore an ACL in Week 10 last year. His return could give the Vikings some stability at right guard. Second-year pro Chris DeGeare is running with the first team now, while Ryan Cook is with the second team. If Herrera returns, he would be the favorite to win the job, although it wouldn't be a lock.

the Vikings' offensive line can use any help it can get. It's getting dominated by the defensive line at this point. That's not unusual this time of year, but there also has to be some level of concern.

Meanwhile, he said cornerback Cedric Griffin (knee) probably will be held out of the first two preseason games as a precaution, but could be ready to go as early as the seond one at Seattle two weeks from Saturday.

Griffin tore an ACL in the NFC Championship game during the 2009 season and then tore the other one in Week 2 of last season. He's been only slightly limited in practice and has looked smooth and fluid when he's on the field.

Meanwhile, other practice highlights include:

  • Undrafted rookie cornerback Marcell Gipson missed practice because of a family emergency.
  • Adrian Peterson returned after the birth of his son, Adrian Jr., and looked like, well, Adrian Peterson. He was powerful, made quick cuts and was, well, you know what he's like. Also for one of the rare times in training camp, Peterson participated in live action, which means tackling to the ground.
  • The defense -- particularly the line -- is light years ahead of the offense, which is understandable. The offense had trouble moving the ball against the defense in short-yardage and goal-line situations. The defense won two of three battles on the goal line (from the two).
  • Christian Ponder continues to work with the second team ahead of Joe Webb. He had his worst day of practice. His accuracy was poor and he threw two bad balls that were intercepted. "It's called being a rookie quarterback in the National Football League," Frazier said. "There's going to be some other days like that." Asked if rookie receiver Stephen Burton ran the wrong routes on the two balls that were picked, Ponder accepted the blame, saying, "I just threw two bad balls."
  • Cord Parks, signed as an undrafted rookie in 2010, got his shot with the first team in place of Griffin. Frazier said it's just a matter of wanted to see how some of the guys down the depth chart look with the first unit. Parks isn't about to move ahead of Chris Cook, the probable third corner.
  • Frazier was happy with the tempo and the intensity of the practice. "A good, spirited practice by the offense, defense and special teams," he said. "It was competitive."
  • Peterson caught several passes out of the backfield. Frazier sees that part of Peterson's game improving enough that Peterson will become an even greater threat, especially on third downs.
  • Ponder on how he sees his progress coming along: "It's coming along, definitely. We're getting a lot thrown at us right now and obviously this is the first year that everyone's been in it. I think so far, so good. I think today kind of was a step back but I think those are the days that you learn the most from. Tomorrow should be a lot better.