In between a 46-minute delay, both starting offenses put together long touchdown drives that ate up more than 9 minutes and were kept alive by a wave of yellow flags.
Altogether, there were 25 accepted penalties, 13 on Seattle and a dozen on Denver.
Ronnie Hillman's 1-yard TD run capped Denver's 14-play, 61-yard drive in which Peyton Manning completed 9 of 11 passes for 63 yards and the officials threw six flags, including one for offsetting penalties.
The drive lasted 9 minutes, 9 seconds - a good two minutes longer than Denver's longest drive last season.
There was even a flag thrown on the ensuing touchback when Seahawks cornerback Jeremy Lane was whistled for taunting. Lane also was whistled for a 31-yard pass interference on first-and-35 play in the second half during a moan-inducing sequence in which penalties were called on five consecutive snaps.
Just when the officials walked off the taunting penalty to Seattle's 10-yard line, the game was delayed for 46 minutes after lightning struck within an 8-mile perimeter of Sports Authority Field, where it was sunny.
After retreating to their locker rooms with 1:30 left in the first quarter, both teams sent their starters back onto the field when play resumed.
The penalties continued, too.
Seattle's 14-play, 90-yard drive that ate up 9:18 was kept alive by four defensive infractions, and Christine Michael's 1-yard run against a mix of starters and backups tied it at 7 following a debatable pass interference call on linebacker Danny Trevathan.
Steven Hauschka's 41-yard field goal gave the Seahawks a 10-7 halftime lead. He was also good from 40 yards after the Broncos went ahead 14-10 on Kapri Bibbs' 3-yard run in the third quarter. Hauschka's 22-yarder gave Seattle a 16-14 lead with 11:22 remaining.
Brock Osweiler's 34-yard strike to Jordan Norwood in stride put Denver ahead 21-16 midway through the fourth quarter. He was 6 for 12 for 85 yards with one TD, one interception and one sack.
Manning finished 10 of 13 for 78 yards with no sacks. Russell Wilson was 4 of 6 for 37 yards for Seattle and was sacked by DeMarcus Ware and T.J. Ford, two thumpers Denver GM John Elway signed in the wake of Seattle's 43-8 thrashing of the Broncos in the Super Bowl six months ago.
The Broncos opened this game better than they did that night in the Meadowlands, when Manny Ramirez's first snap sailed into the end zone for a touchback from which Denver never recovered. This time, the exchange was clean, although Hillman carried for just 1 yard.
Manning was knocked down on his first pass, a 15-yard completion to Demaryius Thomas but his reconfigured offensive line kept him safe after that.
The Broncos were playing without starting running back Montee Ball, who had an appendectomy this week, and they lost backups C.J. Anderson to a concussion. Juwan Thompson (five carries for 59 yards) also was evaluated for a concussion but he was cleared to return.
Notes: RG J.R. Sweezy was the only starter along Seattle's O-line. ... In the Seahawks' backup QB battle, Tarvaris Jackson was 5 of 7 for 47 yards with a sack, and Pryor was 9 of 16 for 137 yards and an INT with 2:35 left. ... Broncos CB Rahim Moore played his first game since suffering from compartment syndrome in his left calf last November and nearly had an interception.