• Statistics | Photos from Reliant Stadium

On an afternoon when middle linebacker DeMeco Ryans was lost for the season, the defense arrived 57 minutes late for work and the opposition seized a 10-point lead with 7:05 left in the game, the Texans were staggering like a fighter who had absorbed one punch too many.

They had allowed 228 yards rushing and three Matt Cassel touchdown passes that helped the Chiefs lead 7-0 in the first quarter, 14-7 at halftime, 21-7 in the third and 31-21 in the fourth.

“What we did today, we couldn’t have done two years ago,” fullback Vonta Leach said afterward.

What they did on a glorious day at Reliant Stadium was to score touchdowns on their last four possessions. The game-winner came with 28 seconds left. Matt Schaub threw a terrific pass to Andre Johnson in the back of the end zone for a 35-31 victory.

“We showed today that this team’s got a lot of fight in it and nothing’s too much for us to overcome,” Leach said.

Including their own defense, which allowed 417 yards.

If not for Schaub, Johnson (eight catches for 138 yards), Owen Daniels (five for 79) and a cast of characters who refused to lose, the Texans wouldn’t be 4-2 for the first time. In their nine-year history, this is the latest they have been tied for first in the AFC South.

Entering their open date, the Texans have scored at least 30 points four times, tying the team record for a season. They put up 35 points on the Chiefs, who hadn’t allowed more than 19 (Indianapolis).

“We showed tremendous heart, and it was led by our quarterback, who is absolutely spectacular,” coach Gary Kubiak said.

Schaub completed 25 of 33 passes for 305 yards and two touchdowns. He didn’t throw an interception. He was sacked twice.

With Schaub on target trying to bring the team from behind, he used the pass to set up the run. The Texans ran for 132 yards, including 71 by Arian Foster, who scored two touchdowns.

Derrick Ward continued his impressive performance, gaining 58 yards on three carries, including a 38-yard touchdown.

“I bet everybody hated us until the last 30 seconds,” said tight end Joel Dreessen, who caught a 5-yard touchdown pass.

Defense rests again

Just when fans thought the defense couldn’t get any worse, it did. And it was horrendous before Ryans suffered a ruptured Achilles’ tendon on pass coverage late in the first half.

Cassel had not engineered a touchdown drive on the road this season, but he did it four times against the Texans. Chiefs receiver Dwayne Bowe usually can’t catch a cold, but he caught six passes for 108 yards and two touchdowns.

“We’re struggling on defense,” Kubiak said. “I can’t hide it from myself or anybody. We’ve got to tackle better and cover better. We’ve got to do everything better.”

Usually, the one thing the Texans can count on is their run defense. They ranked fifth entering the game.

Thomas Jones (19 carries, 100 yards) posted his second 100-yard game at Reliant Stadium in two seasons. Port Arthur native Jamaal Charles (16 for 93) was just as dangerous as Jones.

In all fairness, the comeback couldn’t have been pulled off without the defense.

In the fourth quarter, Foster and Jones traded touchdowns, and the Chiefs led 31-21 with 7:05 left. Then Schaub took the Texans 86 yards in eight plays, with Foster’s second touchdown in the quarter making it 31-28.

That’s when the Texans needed a clutch series by the defense. And that’s what they got.

The Chiefs faced third-and-2 at their 41 with 2:36 remaining. But rather than run Jones or Charles, coach Todd Haley went for the pass, and Cassel overthrew tight end Tony Moeaki.

“I was a little surprised they’d do that (pass),” Kubiak said. “It saved me a timeout and got us the ball back.”

The Texans started at their 20 with 2:22 remaining.

“It was a dogfight, and guys just kept swinging,” offensive tackle Eric Winston said.

Going for the win

A 31-yard completion from Schaub to Johnson gave the Texans a first down at the Kansas City 24, well within Neil Rackers’ range if they wanted a field goal to force overtime.

“No way were we going to overtime,” offensive tackle Rashad Butler said. “We were determined to win it right there.”

Daniels got them a first down at the 13 with an 11-yard catch. After Foster ran for 2 yards, Schaub was flushed from the pocket. He ran to his left and made the difficult throw to Johnson in the back of the end zone.

The Chiefs still had a pulse. With 4 seconds left, the Chiefs reached the Texans’ 38. Time for one last pass into the end zone, but Amobi Okoye chased down Cassel and sacked him for a 12-yard loss to preserve the victory.

john.mcclain@chron.com