ST. JOSEPH, Mo. -- It has been years since the Kansas City Chiefs gave their fans any reason to stick around after halftime of their preseason opener, when the starters and backups generally take a seat.

That will change Friday night.

Chiefs coach Andy Reid plans to give each of his quarterbacks a full quarter against the San Francisco 49ers. That means Alex Smith will start and veteran backup Tyler Bray will get the second quarter, while first-round draft pick Patrick Mahomes II will start the second half.

It's arguably the most anticipated preseason debut by a Chiefs rookie since 1983, which also was the last time Kansas City spent a first-round draft pick on a quarterback.

Asked what he wants to see out of his young signal caller, Reid replied: "I'd tell you this with everyone: Execute. Obviously, the quarterbacks have a little more responsibility with all the calls and so on, but the main thing is to execute."

Reid said most of the starters would play the first quarter alongside Smith, while the backups on the depth chart this week will have Bray under center. So whatever the outcome for Mahomes is Friday night, it must be examined through the prism of working with third-team players.

Likewise, it will almost certainly come against the second- and third-team 49ers defense.

That's one reason Reid was reticent Tuesday following the Chiefs' final open practice of the week to put too much stock in a single preseason game. He instead will lump the performances in a game setting along with what he's seen out of practice and the meeting rooms, and begin deliberating with his coaching staff on what will ultimately constitutehis 53-man roster.

With changes to the cutdown rules, he'll also have three more games to examine.

"The first preseason game, everyone has an opportunity to play. After that, it's not guaranteed," Reid said. "That kind of stuff has never changed. The thing you don't want to do is give another team, if possible, a good player. You want to make sure you do as thorough evaluation as you can."

Several starters are also unlikely to play because of injuries, and at least one of them could force the Chiefs to make a roster move ahead of their preseason opener.

Reid indicated kicker Cairo Santos could be out while nursing a groin injury.

"We'll just monitor it and see how he does," said Reid, who had former Stanford kicker Conrad Ukropina and Liberty's John Lunsford in for an audition. "We've got some kickers that are here to come in. We'll work those guys out just in case he can't go in this game.

"Other than that," Reid said, "he's going to be fine. It's not a serious deal."


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Most of the other injury woes have occurred on defense.

Rookie lineman Tanoh Kpassagnon was the latest to go down with what Reid called shin splints. DT Bennie Logan has already been out with a knee injury, while second-year pro Chris Jones remains on the PUP list following offseason knee surgery.

DT Roy Miller, signed last week, continues to work his way back from a torn Achilles tendon sustained last October. He has yet to practice with the team.

In the secondary, star safety Eric Berry is unlikely to play while dealing with a heel injury that has sidelined him since Saturday. Cornerbacks De'Vante Bausby (ankle) and Jacoby Glenn (concussion) are also out, while linebackers Tamba Hali and Dadi Nicolas remain out with knee injuries.

The positive of all those injuries is that others will have an opportunity to stand out.

"You get to see them with the swings that happen in games. That is really what it is all about," defensive coordinator Bob Sutton said, "is how you deal with these swings and can you get your focus right back in. Can you let that play go, good or bad, and get right into it? Or hey, we have had two or three series that have not gone the way we wanted it to go on defense. So can we get this thing back on track and get in position to win the game?

"We have a lot of young guys," Sutton said, "so I think it will be exciting to see them."