MANKATO, Minn. -- A daily review of the hot topics coming out of Minnesota Vikings training camp:

• Coach Mike Zimmer said the Vikings came out of Friday's preseason opener relatively healthy, but the Vikings were missing several players at practice on Sunday afternoon. Defensive tackle Tom Johnson and linebacker Dom DeCicco weren't on the practice field, and safety Mistral Raymond (who suffered a concussion during Friday's game) was doing work on the side with safeties Robert Blanton and Jamarca Sanford, who missed Friday's game with hamstring and back injuries, respectively. Defensive tackle Linval Joseph, of course, was not practicing after a stray bullet struck him in the calf in a nightclub incident on Saturday morning. On a more positive note, cornerbacks Josh Robinson and Marcus Sherels returned from hamstring injuries, and tight end Chase Ford (broken foot) was once again out of a walking boot.

• The Vikings began their practice outside, but had to move indoors for the first time during training camp thanks to a jagged bolt of lightning off to the west of their practice field. That turned Sunday's session into a glorified walk-through, and the Vikings were only able to do so much work inside the Minnesota State field house. Zimmer said he hadn't written practice schedules for this week until after Friday night's game, and the Vikings will have to resume the work of drilling their mistakes once they get back outdoors on Monday.

• Zimmer wasn't thrilled with the way the Vikings' secondary played the run, particularly on Darren McFadden's 23-yard burst at the end of the first quarter. Safety Antone Exum had a shot at McFadden at the Raiders' 29, but came down with inside leverage and couldn't fight through McFadden's stiff arm to bring him down until the Raiders' 43. "I tell our guys all the time that long runs are typically because of the perimeter run force," Zimmer said. "We did not do a good job when the safety was coming downhill on that play, so we ended up giving him 14 more yards on that run than we should have."

• Wide receiver Adam Thielen continued to win praise for his work on special teams, after returning three punts for 53 yards and making a tackle for a 4-yard loss on a punt at the end of the first half. Thielen was visibly upset he didn't score on his second return, which went for 26 yards, but special teams coach Mike Priefer said that was just a matter of Thielen making one more move. "He is probably disappointed that he didn’t score on the one, but that’s something that a young punt returner, that’s a mistake they are going to make," Priefer said. "He saw the seam and he just went for it full speed. He’s got to kind of dip and go to the outside or widen them and go back inside but it was a very, very well-blocked play." Priefer said Sherels is still entrenched as the Vikings' punt returner, but with Sherels fighting a hamstring injury, it's not bad for the Vikings to have another option they trust.

• Rookie defensive tackle Shamar Stephen did well in Friday's game, Zimmer said. He wound up with five tackles in the game and showed some nice push up the middle on a couple run plays. With Joseph likely to miss some time, the seventh-round pick could see some more opportunities.