Danica Patrick became a worldwide sensation as a rookie at the Indianapolis 500, challenging for victory and becoming the first woman to lead laps in the showcase race.

Those Indy days are fading fast.

Patrick's shift to stock cars is long under way and her ties to IndyCar were cut even further Monday — she said she won't run in this year's Indy 500.

Her focus is entirely on NASCAR, and on May 27 she'll race in the Coca-Cola 600. She said skipping the Indy 500 was a "business decision."

"I hope to do it in the future, the Indy 500 that is, and maybe it will be a double," she said. "But at this point in time, after a lot of conversations, it's just going to be the Coke 600 and I think it's going to be a big challenge. It's just is something that didn't work out, as far as the business side of things. ... For this year, it just didn't happen."

Patrick led 19 laps late and finished fourth in 2005. She was a career-best third in 2009.

When she jumped full time to NASCAR she said the Indy 500 was still under consideration. Her NASCAR season includes the full second-tier Nationwide Series schedule for JR Motorsports and 10 races in the elite Sprint Cup Series for Stewart-Haas Racing.

Patrick had previously announced eight of her races. The Coca-Cola 600 — Patrick jokingly called NASCAR's longest event of the season "The Coke 6,000," — is the ninth announced race. The Indy 500 and the Coca-Cola 600 are both May 27.

"We didn't tell her she couldn't run the 500. It was left up to her," team co-owner Tony Stewart said. "It shows how dedicated she is to making this transition."

Stewart, Robby Gordon and John Andretti have all tried to run both events on the same day. Stewart, NASCAR's three-time champion, completed the double twice: In 1999, he was ninth at Indy and fourth at Charlotte, and in 2001, he was sixth at Indy and third at Charlotte.

He's not tried Indianapolis since, and has let go of his childhood dream of winning the 500. He has twice won the Brickyard 400, NASCAR's race at the storied Indianapolis Motor Speedway.

"The hard part for me was you make that decision when you sign up to do (NASCAR)," Stewart said. "The decision you make, you have to come to peace with yourself with saying 'I'm not going to do this.' That was my childhood dream anyway. It may be a different scenario and feeling for her. But it was hard knowing when I signed that (NASCAR) contract that I was writing off the opportunity to go race at Indy.

"It's figuring out at the end of the day what do you really want to do. I guess that's the part that even though it was hard to watch opening day of practice at Indianapolis, I'm enjoying what I'm doing, too, and this is what I want to do at the end of the day," he continued. "It makes you want 30-hour days and 400-day years and we always want to do more than what we're capable of doing, but the reality is you have to pick at some point and choose your career path. This is what I've done and what she's doing now."

But Stewart said so long as Indianapolis Motor Speedway makes it logistically possible for Patrick to attempt both races, she may eventually run the race again. He said he has no interest in fielding a car for her, citing how much he's already doing with all his other teams.

The IndyCar Series would also welcome back its most recognizable driver to its biggest event of the season.

"We continue to wish Danica the very best on this new phase in her career. The door is always open should she wish to run the Indianapolis 500 in the future," IndyCar CEO Randy Bernard said in a statement.

Patrick has already set some of her expectations for NASCAR, and sounded Monday as if she expects her debut in the Daytona 500 next month to go as well as her debut in the Indianapolis 500. She tested there two weeks ago with new crew chief Greg Zipadelli, and after leading 13 laps at Daytona in last July's Nationwide race, likes her chances in the Feb. 26 season opener.

"At Daytona, the cars are very fast, so I feel good about that race," she said. "I was lucky enough to get to run with Tony in the Nationwide race last summer and that went pretty good, so I feel good about Daytona and I think there's a real chance, if luck falls our way, to perhaps win.

"I think it's a real chance. I mean a guy like Trevor Bayne last year showed that. Those are the expectations for the first race."

Bayne, a rookie last season, was the upset winner of the Daytona 500, which Stewart said was proof that Patrick is a viable contender.

"A rookie won it last year, why would you ever count yourself out?" he asked. "She's a talented driver. Our cars were really fast at Daytona. At that point, I'd have that confidence."

But Stewart is cautious regarding his expectations for Patrick. Although she said she'd like to knock down top-20 finishes in the Cup Series, the car owner was more concerned with Patrick simply turning laps and learning as much as she can before her scheduled full-time move to the Cup in 2013.

"I crashed everything that I drove when I drove the Nationwide cars. We got to the Cup side and it got better, obviously," Stewart said. "But I think looking at it, these 10 races for her this year, for me, it's just finishing the races and just getting the track time. I'm not worried about what her finish is at the end of the day.

"I think the success at the end of the year won't be judged by where the finishing positions are at the end of the day, as much as what she takes away from each race weekend. That's what my goal is for her."

Patrick has higher goals for the Nationwide Series, where she's run 25 races over the last two series. She has three top-10 finishes and one top five, all last season with JRM. The Daytona 500 will be her Cup Series debut.

"With the Nationwide stuff, it very much depends on the individual weekend itself. There are still some tracks that I haven't raced before, so probably a little bit different expectations for those," she said. "But, for the most part, solid top 10s and getting into the top five consistently through the year would be a goal. And I'd like to get to Victory Lane."