KANSAS CITY, Mo. (AP) — With a playoff spot on the line, Chiefs quarterback Alex Smith will miss Sunday’s game against the San Diego Chargers because of a lacerated spleen, he said Friday.

Chase Daniel will start in Smith’s place for only the second time in two seasons.

Smith was likely hurt on a hit early in the third quarter of last weekend’s 20-12 road loss to the Pittsburgh Steelers, but he didn’t feel any pain at the time. He wasn’t diagnosed until undergoing a scan Thursday after several days of what felt more like a stomachache than a serious injury.

The quarterback will not need surgery and is expected to fully recover, but Smith would miss a potential playoff game.

If the Chargers beat Kansas City, they clinch a postseason berth. The Chiefs would need to win and have Baltimore and Houston lose to make the playoffs.

Smith didn’t notice anything was amiss Sunday until after he’d showered and the adrenaline had worn off. Experiencing cramping and pressure, Smith was checked out by the medical staff, but he didn’t exhibit the telltale signs of a lacerated spleen.

Smith practiced twice this week, feeling fine other than some nausea. A stomach virus had been going around the team, so he and the medical staff suspected it might be that.

By Thursday, though, he hadn’t gotten any better. Smith didn’t want to take time away from his family on Christmas, but a team doctor helped persuade him to undergo the scan.

Daniel has one career start in six NFL seasons — which happened to come against the Chargers in last year’s regular-season finale. With the Chiefs locked into the No. 5 seed, Smith rested that day. Daniel went 21 of 30 for 200 yards with a touchdown and no interceptions and rushed seven times for 59 yards in a 27-24 overtime loss that got San Diego into the playoffs.

Smith has thrown for 18 touchdowns with six interceptions this season.

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