The Indianapolis Colts are awaiting further test results, but the early prognosis is not good for running back Marlon Mack.

Playing on the final year of his rookie contract, the 24-year-old left Sunday’s 27-20 loss against the Jacksonville Jaguars with an ankle injury after catching a 3-yard pass midway through the second quarter. Colts head coach Frank Reich said Mack is dealing with an Achilles’ tendon injury and will undergo an MRI on Monday.

Mack was expected to play a major role in the Colts’ offense this year, sharing the workload with rookie Jonathan Taylor and hurry-up specialist Nyheim Hines. With veteran quarterback Philip Rivers under center, he was expected to be a much bigger part of the passing game and showed good strides in that direction throughout training camp.

Indeed, Mack had four carries for 26 yards and three catches for 30 yards at the time of the injury.

Hines finished with a team-high 29 yards on seven carries, and Taylor carried nine times for 22 yards. Indianapolis finished with just 88 yards on 22 attempts overall.

“We never quite got into a rhythm there, for a variety of reasons,” Reich said. “We were having some success early in the pass game. We had a lot of chunks in the pass game and felt like we were almost moving the ball at will and felt like we couldn’t be stopped on offense. I really felt that way.

“Felt like Philip was really deadly accurate, and we’re making plays. Parris (Campbell) made a bunch of plays, and the ball was getting spread around. So we just didn’t dial up a couple runs that we sometimes do, but that’ll change game to game.”

Rivers finished 36-of-46 for 363 yards with one touchdown and two interceptions. He completed passes to nine receivers including Hines (team-high eight for 45 yards) and Taylor (six for 67 yards).

Taylor, a second-round pick out of Wisconsin, saw substantial playing time in the second half and likely will be asked to carry a much bigger load for however long Mack remains sidelined.

He said he’s up to the challenge, thanks to the relentless effort of running backs coach Tom Rathman to get him up to speed.

“When I did get in, I felt like I was prepared,” Taylor said. “I mentioned it earlier, Coach Rath has done a tremendous job as far as making sure that everything is 100% crystal clear as far as throughout the meetings, throughout training camp and up until the game to make sure that I fully understood the game plan and everything that’s supposed to be going on.

“And then it’s just about execution. And, at this level, I found out early it’s good-on-good, so you gotta make sure that the small little details are what sets you apart.”

PASS REGRETS

Veteran wide receiver T.Y. Hilton caught four passes for 53 yards, but it was two that got away he’ll remember most.

Rivers looked to Hilton twice on the team’s final three offensive snaps as Indianapolis tried to tie the game in the final minute from Jacksonville’s 26-yard line.

Hilton appeared to make a catch along the sideline inside the Jaguars’ 10-yard line on the first attempt. He got both feet in but couldn’t control the catch as he fell out of bounds.

Rivers tried to take the blame on the fourth-down pass, saying it arrived late. But Hilton couldn’t hold on inside the 20 and was brief and to the point in his postgame Zoom interview.

“I lost the game,” Hilton said. “… Two drops. Never should’ve happened.”

TAKING A KNEE

The Colts wore “Black Lives Matter” T-shirts during pregame warmups and remained on the field for the playing of “Lift Every Voice and Sing” and “The Star Spangled Banner” prior to the game.

During the latter, players and coaches linked arms in unison while Reich kneeled a step in front of the group. It was the latest step in the team’s ongoing effort to support the Black community in the wake of the deaths of George Floyd and Breonna Taylor and the shooting of Jacob Blake during encounters with police.

“We’re not talking to the Black community,” linebacker Darius Leonard said. “We’re talking to white men who are in power. Frank is the leader of this team, and he’s in power to his team, and we’ve got to take that step forward, and he’s the one who says, ‘You know it starts with me.’

“You never know how it amplifies, so it definitely means a lot for someone like that to step up and say, ‘OK, I’m going to take a stand for you guys.’ That definitely means a lot, and that’s why we stand behind Coach Frank, he stands behind us and we all stand together.”