Jay Ajayi told reporters late Thursday that he's not “overly concerned” about the chest injury that prematurely ended the best game of his rookie preseason.

Either Ajayi was putting on a brave face or has an incredible tolerance for pain.

Ajayi cracked a rib during the Dolphins' 22-17 loss to Tampa Bay Thursday -- yet another setback in a summer that hasn't gone according to plan.

Ajay missed a good chunk of training camp with a hamstring injury, but finally broke through late Thursday. He carried the ball nine times for 66 yards and also caught two passes for 37 more out of the backfield.

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“I thought he ran hard,” Dolphins coach Joe Philbin said. “He made a guy or two miss, showed toughness inside, and caught the balls that were thrown to him, which is always a good place to start.”

It was the kind of performance scouts anticipated after Ajayi's standout junior season at Boise State. Ajayi was supposed to be a second or third-round draft pick in the spring, but slipped to the Dolphins in the fifth because of long-term injury concerns about his knee.

Ajayi was projected to make the team on draft pedigree alone, and probably still will. But the latest development could allow the Dolphins to stash Ajayi, who struggled to break through before Thursday night, on injured reserve for the season. And if they do, it could potentially re-open the door for Mike Gillislee, who also had a big game against the Buccaneers.

Gillislee spent his entire rookie season on injured reserve and before Thursday, looked to be the odd man out of the Dolphins four-back race to back up Lamar Miller. Damien Williams and LaMike James are more likely than not to make the team.

These are all decisions the Dolphins must make by 4 p.m. Saturday, when their roster must be pared from 75 to 53 players. Cuts began early Friday, with Anthony Johnson the biggest name waived. Johnson had been in a three-way competition with C.J. Mosley and A.J. Francis for the fourth (and possibly fifth, if Miami keeps that many) defensive tackle job.

Also cut Friday: OLs Michael Liedtke and Donald Hawkins, WR Damarr Aultman, DT DeAndre Coleman and LBs James Davidson and Jeff Luc. Josh Freeman has also been released after a failed comeback attempt, Bleacher Report first reported.

Just a few of the questions left unanswered:

▪ Will Andrew Franks (or a kicker from outside the organization) unseat Caleb Sturgis?

▪ Did Matt Hazel show enough to convince the Dolphins to keep six receivers, even with DeVante Parker’s return?

▪ Is there a place on the roster for Jordan Tripp or will Miami go with their undrafted rookies at linebacker?

▪ Will the Dolphins keep seven cornerbacks or is Will Davis on the way out?

▪ And is Miami’s eventual third tight end currently a member of another team?

“We evaluate after every preseason game, we evaluate after the scrimmages, we evaluated after the Carolina practices even before we played the game,” Philbin said. “It’s a constant process.”

Miami Herald sports writer Barry Jackson contributed to this report.