Mother Nature made her presence felt on the opening day of Lions' training camp, but the deluge outside Detroit's indoor practice facility couldn't dampen the spirit of what Jim Schwartz described as a “good start” to a crucial season for a team looking to become a perennial playoff contender. Cornerback Chris Houston outlined the goal coaches relayed to players for the season in a simple statement that stressed discipline as a key to the team's progress: “We made the playoffs [in 2011], let's try to get one more game,” he said. “[Coach Schwartz] showed us the statistics on penalties, and we need to cut down on that and get past good to be great.”

Who's here: 89 of the 90 players on Detroit's roster reported on time, and all but five of them participated in practice Friday. The two most notable participants among the active players were LB Stephen Tulloch and RB Mikel Leshoure. Tulloch missed all of Detroit's OTA workouts with knee tendinitis. His participation reinforced his assertion that the decision to rest him during the offseason was strictly precautionary. RB Mikel Leshoure participated fully in drills for the first time since rupturing his achilles in training camp last season. All five players that were placed on Detroit's PUP list were present at practice. T. Jonathan Scott, RB Jahvid Best, DE Ronnell Lewis, and CB Chris Greenwood watched the workout. WR Ryan Broyles worked with trainers as he continues his ACL rehab.

Who's not: DE Cliff Avril was the only Lions' player who failed to report for the start of camp. Avril has yet to sign his one-year, $10.6 million franchise tag tender. He hasn't offered a timeline for when -- or if -- he'll report to camp, and has hinted that he could miss several weeks of the preseason before joining the team. Schwartz said Thursday that he wouldn't allow Avril's absence to hurt Detroit's progress. That statement gained credence Friday when DE Lawrence Jackson filled in ably for Avril during first-team drills. Jackson missed several games last season with a thigh injury, but he looks healthy heading into 2012. If Jackson can elevate his level of play, he could provide the team with an attractive alternative to Avril next season if a long-term solution to the impasse between Avril's agent and the Lions can't be reached.

Follow Lions reporter John Kreger on Twitter: @CBSSportsNFLDET and @johnkreger.