KANSAS CITY, Kan. — Danica Patrick walked through the pits with quick, purposeful steps. Her head barely moved, eyes masked behind designer sunglasses as she worked her way toward the team trailer.

Patrick stepped behind a barricade, signed about a half-dozen autographs and curtly answered a TV reporter’s questions before disappearing into the hauler after a few seconds.

The tears of joy from a historic win a week earlier were long gone Sunday, replaced by frowns and frustration after a mechanical failure on the 157th lap knocked Patrick out of the RoadRunner Turbo Indy 300 at Kansas Speedway.

“I am disappointed that the Motorola car had to cut the day short due to the right rear wheel mount,” Patrick said. “I came on the radio earlier in the race saying there was some movement in the car, but we had no idea that it was that serious.”

Patrick became the first woman to win an IndyCar race last week in Motegi, Japan, a victory that came in her 50th career race and set off an unexpected emotional outburst. A weeklong flurry of TV appearances, dozens of interviews, even a movie premiere followed, and she kept the momentum going on the track by qualifying third for the Kansas race.

The good vibrations came to an abrupt end once the race started.

Fighting a poor-handling car for most of the day, Patrick never threatened the lead and hovered between seventh and 12th for most of the race. Her day ended during a yellow-flag pit stop when the crew was unable to remove the right rear wheel and had to shut the car down.

Clearly frustrated, Patrick quickly climbed out of the car and raised her hands as if to say “what happened?” before walking away.

“We had a right rear mechanical failure,” was all Patrick could muster when asked what happened.

Patrick’s day was rough from the start, with Tomas Scheckter squeezing her inside the white line seconds after the green flag. She stayed close to the leaders for a while, but a pit stop during a caution on Lap 25 led to handling problems and she quickly starting losing spots.

Dropping as low as 14th, Patrick made up some ground after another pit stop midway through the race, but never could get the car to go as fast as she wanted and bounced in and out of the top 10.

“We came into the race with a great car, and struggled to stay up front from the beginning,” Patrick said.

She almost crashed, too.

Trying to pass a slower car on Lap 130, Patrick was forced up near the wall when Marco Andretti tried to squeeze between her and the other car. Patrick wobbled for a few seconds in the slick “gray” part of the track, then worked her way back down, barely saving the car from hitting the wall.

“I got caught in the gray and I was out of the throttle for an eternity and lost a whole straightaway,” she said. “That was disappointing. I got back going and I was: ‘This is exciting rear-end stuff going on here.’”