GREEN BAY, Wis. - The momentum was theirs. All the Jets had to do was finish.

But they not only squandered an 18-point lead but self-destructed in a 31-24 loss to the Packers on Sunday at Lambeau Field.

The loss of star defensive end Muhammad Wilkerson (ejection) and No. 1 wide receiver Eric Decker (hamstring injury) hurt in the second half. But in the end, the Jets were done in by an innocent mistake by Sheldon Richardson, who simply was trying to help out his coaches.

A potential tying 36-yard touchdown pass from Geno Smith to Jeremy Kerley on a fourth-and-4 was negated when offensive coordinator Marty Mornhinweg initially signaled for a timeout before the ball was snapped with 5:06 remaining. Richardson, however, didn't see Mornhinweg back off on the call and whispered "timeout'' in a game official's ear, resulting in the play's being called dead.

"I let the team down,'' Richardson said in a near-empty locker room. "I could have given us another chance to keep fighting.''

Per team rules, Jets assistants are not permitted to speak after games -- which left Richardson and other players to field the questions about the bizarre ending to a winnable game.

Richardson said he had "no idea'' why Mornhinweg tried to call timeout, but in the moment, the reason didn't matter. "I was just trying to help the team out as best as I can,'' he said.

"It was fourth down in Lambeau Field and it was 80,000 screaming. They didn't hear Marty. So I made sure they heard him. It was my fault.''

The gaffe capped a head-scratching second-half performance by the Jets (1-1), who let the Packers (1-1) rally from a 21-3 deficit. But while Richardson's timeout call eradicated a touchdown, the Jets' total lack of discipline was really to blame.

"Obviously, this is a rough one, to say the least,'' coach Rex Ryan said. "It's my responsibility. I've got to make sure we know exactly what our assignments are and how to play them.

"It will get done. One thing I know about this team, this team's got heart. There is no question about it. The effort will be there and that's why I believe we can get it fixed.''

Wilkerson smiled and waved at the crowd as he left the field after his third-quarter ejection for throwing punches. But there was nothing funny about his departure or the Jets' inability to contain Jordy Nelson. He caught nine passes for 209 yards, including an 80-yarder for a touchdown that broke a 24-24 tie with 2:08 left in the third quarter.

The game couldn't have started any better for the Jets, though. They led 14-0 after 6:36, and before long, they were up 21-3. Everything seemed to be clicking for the 81/2-point underdog.

Tempers were simmering early and emotions boiled over after Aaron Rodgers (346 yards, three touchdown passes) hit Randall Cobb for a 1-yard touchdown with 5:45 left in the third that gave the Packers their first lead, 24-21. A skirmish broke out in the end zone after Rodgers connected with Cobb again on the two-point conversion.

Richardson, in the middle of the action, was flagged for unsportsmanlike conduct. Wilkerson, who also was hit with an unsportsmanlike-conduct penalty, was thrown out.

The Jets tied it at 24 on Nick Folk's 52-yard field goal, but Nelson delivered the dagger 13 seconds later. He beat cornerback Dee Milliner on a double-move, eluded rookie safety Calvin Pryor and easily scampered 80 yards to the end zone.

The Jets, it appeared, were finished -- until Kerley caught a beautifully thrown pass from Smith for a 36-yard score to apparently tie it. But little did Ryan know that Mornhinweg had run down the sideline signaling a timeout -- and that Richardson had made sure it was granted.

"They said I called it. I never called it,'' Ryan said.

Kerley said he could see coaches on the field with his peripheral vision, so he knew time had been called. He ran the route and caught the ball anyway.

"I was a little upset. It's a touchdown, so I definitely wanted to get that,'' he said. "But I was upset I didn't make the last catch on the last play of the game. That was a ball I should've caught.

"It's a tough loss, it's an upsetting loss. I think we were in the game the whole time. But we came out flat in the second half.''