JACKSONVILLE, Fla. -- Daniel Jones helped spark a massive turnaround in the Indianapolis Colts' offense through the first half of the season.
Now, as Indianapolis sputters to the finish line, Jones will be a spectator.
The Colts quarterback, who helped engineer an offense that was on a record trajectory through eight weeks, suffered a season-ending Achilles tear in the first quarter of Sunday's 36-19 loss to the Jacksonville Jaguars, sources confirmed to ESPN. He's set to undergo surgery.
The injury and the subsequent defeat leave the Colts in a daunting situation, with a rookie backup quarterback under center, a brutal stretch run ahead and dimming playoff hopes.
"That's our team leader, our team captain," wide receiver Alec Pierce said. "It's brutal."
Jones dropped back to pass late in the first quarter on the rain-soaked field and seemed to make an awkward step as he delivered the ball. He quickly fell to the turf and immediately grabbed the back of his lower right leg. He reacted with frustration, forcefully slamming his helmet to the ground as athletic trainers gathered around him.
After a brief examination in the medical tent, he departed to the locker room and was ruled out of the game minutes later.
Indianapolis coach Shane Steichen, asked afterward about the specifics of the injury, did not officially confirm Jones had sustained an Achilles tear but indicated the team was bracing for the worst.
"It could be season-ending," he said. Asked to elaborate, Steichen said, "It's not looking good."
Jones already had been playing through what was believed to be a hairline fracture in his left fibula -- the opposite leg -- and had played the past two games in spite of what is described as a painful injury. The fibula injury had limited Jones' mobility, but he appeared sprier in the early stages of Sunday's contest.
"Daniel's the toughest guy that I've ever been around, by far, in my life," Colts rookie backup quarterback Riley Leonard said.
Leonard completed 18 of 29 passes for 145 yards in relief of Jones in his first meaningful action since being drafted in the sixth round out of Notre Dame in May. Leonard lauded Jones for coming back to the sideline after his injury and helping to coach Leonard during the game.
"He's the most competitive person that I've ever met," Leonard added. "So, it's no surprise that he came back out there.
"He was the first one to put the rain gear on me, the first one to ask me what I saw on that play and help me out. It's just exactly who he is, whether he's playing or not."
Unfortunately, none of that will help the Colts address their dire situation.
They lost the AFC South lead with Sunday's defeat, as Jacksonville now takes sole possession of first place. Indianapolis has dropped four of five and has a tough remaining slate: at the Seattle Seahawks, home against the San Francisco 49ers and Jacksonville, then at the Houston Texans. The Colts could be bumped out of the seventh and final AFC playoff spot in the current standings depending on the outcomes of the Texans' game Sunday evening and the Los Angeles Chargers' outing Monday night.
After starting 7-1, the Colts are in a dramatic free fall and have to find answers -- fast.
"That'll be the challenge this week," Pierce said. "Refocus. That past, there's nothing we can do. We knew the magnitude of this game. We needed to win this one.
"But all we can do is focus on the next one."
Steichen agreed.
"We've got everything we want still in front of us. We've got to go," the coach said. "So, we've got to get this thing cleaned up and get ready for Seattle. We've got a big one on the road. That's the message today."
PFT first reported that Jones suffered a torn Achilles.