Chiefs running back Thomas Jones, top, leaps over the pile to score a two-yard touchdown in the fourth quarter. The Chiefs won, 27-13, Sunday in St. Louis.

St. Louis ? Matt Cassel was supposed to be a game-day decision. The quarterback had no doubt he’d be in the lineup.

Cassel went the distance only 11 days after an emergency appendectomy, leading the way in a 27-13 victory over the suddenly sagging St. Louis Rams on Sunday. He didn’t think it was a big deal, either.

“Everything felt good,” Cassel said. “I feel good now. And a win makes it feel better.”

Before the game, Cassel said one of the team doctors texted that he was probably more nervous than the quarterback about what might happen. Teammates were impressed at the quarterback’s toughness, too.

“For a guy to come back after having an organ removed from his body, playing the next week, yeah, it’s definitely extraordinary,” running back Thomas Jones said. “I’m proud of him, really proud of him.”

To the Rams, Cassel didn’t look a man who’d just been stitched up.

“He’s a tough dude,” defensive end Chris Long said. “I mean, he came out there and slung it around a little. He took a hit or two.

“A lot of people wondered if he’d even play, and he played a good game.”

Jamaal Charles scored on a short run and helped clinch it with a late 80-yard burst for the Chiefs (9-5), who retained a one-game lead over the Chargers in the AFC West.

Kansas City managed only 67 yards in a 31-0 loss at San Diego last week with backup quarterback Brodie Croyle starting, and ended a seven-quarter scoreless drought on Cassel’s two-yard pass to Leonard Pope midway through the second quarter.

Jones became the NFL’s 25th player to rush for 10,000 yards and scored the final touchdown on a two-yard run with 3:26 to go, one play after Ron Bartell ran down Charles just shy of the goal line. Charles had 126 yards on 11 carries and Jones had 62 yards on 22 carries, and the Chiefs totaled 213 yards rushing.

Cassel was questionable after getting limited work in practice, but led the team on the field for warmups and didn’t miss a snap while going 15-for-29 for 184 yards. He was rarely hit by the Rams, who sacked him twice on the same series in the third quarter but couldn’t rattle him, and even produced a first down with a 13-yard scramble in the second quarter.

The Rams (6-8) fizzled after a strong start, losing their second straight and missing a shot to solidify first place in the weak NFC West. Sam Bradford became the third rookie in the NFL to pass for 3,000 yards but it came in one of his worst performances.

“I didn’t play well at all,” Bradford said. “We let it get away and there’s nothing we can do about it now.”

Bradford was 21-for-43 for 181 yards and two interceptions, both times by Kendrick Lewis. Bradford was sacked three times, all by Wallace Gilberry, to lead a pass rush that hounded him all day.

The Rams led 6-0 after field goals to end the first two possessions but totaled one first down in the second and third quarters while the Chiefs scored 20 straight points.

St. Louis got its first five first downs of the second half on a 12-play, 72-play, drive capped by Steven Jackson’s five-yard run that cut the margin to 20-13 with 4:04 to go on. The next play after the kickoff, Charles broke loose for an 80-yard jaunt to the Rams two, and Jones took it in the next play.

“When you have eight men in the box, you usually don’t get those types of runs,” Bartell said. “We shot ourselves in the foot a couple of times.”

The Chiefs have won five straight in the series since 1997, and were helped in this one by thousands of vocal fans who made the trip across Interstate 70. Gov. Jay Nixon attended and presented the Governor’s Cup trophy, usually awarded after a preseason game.

The Rams had five false starts. Bradford said “for a home game it was a little harder to hear.”

“We’ve got to be better than that,” the quarterback added. “I didn’t think I played well at all.”

Jones, who alternates with Charles, hit the 10,000-yard plateau on a four-yard carry early in the third quarter. Jones entered the game needing 17 yards and finished with 62 yards on 22 carries after totaling 1 yard on three attempts last week.

Two field goals by Josh Brown field goals in the first quarter ended the Rams’ three-game slow-starting slump during which opponents outscored them 30-0 the first two possessions. The Chiefs managed only 16 yards on nine plays in the first quarter, and Cassel threw into a crowd on an interception by Kevin Dockery to end the second series, but outgained St. Louis 155-8 in the second quarter.

Offensive tackle Jason Smith was whistled for three penalties in the first half — false start, illegal use of hands and holding.

The Chiefs finished 3-5 on the road. They allowed an average of 32 points the previous five road games.

Notes: Rams FB Brit Miller was carted off with a right knee injury in the third quarter and is likely out for the season. … Bradford is third on the single-season rookie QB list in completions (307), attempts (517) and yards (3,065). … Chiefs WR Dwayne Bowe had two catches for 53 yards after totaling one catch for 3 yards the previous two weeks. … The Chiefs had 48 yards rushing on 17 carries at San Diego.