If Helio Castroneves is feeling the pressure heading into this weekend's MAVTV 500, he's not letting it show.

The fun-loving Brazilian has been his jovial self ever since his IndyCar Championship hopes took a huge blow two weeks ago at the Grand Prix of Houston. Castroneves entered the doubleheader weekend with a 49-point lead over Scott Dixon, but after several mechanical failures led to disappointing finishes, Castroneves is now 25 points behind Dixon entering the final weeekend of the season.

Right after the disastrous doubleheader in Houston, Castroneves jokingly tweeted this photo to Dixon:

A few days later Castroneves retweeted this image, of him and Dixon as boxers preparing for a title bout:

On Thursday Castroneves, who won the fifth season of Dancing With The Stars, tweeted a link to a recent performance to Neon Trees' "Everybody Talks."

Not exactly what you might expect from an athlete who just saw his first championship slip out of his grasp. Castroneves' Twitter activity is in stark contrast to, say, LeBron James, who stopped tweeting during the 2013 NBA playoffs in order to focus on basketball.

But to each his own, and in an interview with ThePostGame on Thursday Castroneves sounded relaxed but determined.

"I’ve got nothing to lose," Castroneves said. "We feel that we have not only the car but the team behind it to make [a victory] happen."

As recently as last month, few thought Castroneves would be in this position. The 38-year-old had led the standings for 14 of the 18 races this year and could practically coast to his first IndyCar Championship. But mechanical failures led to 18th and 23rd place finishes in Houston. Dixon pulled ahead of Castroneves after the weekend, and Castroneves needs a lot of help if he wants to surpass Dixon on Saturday at the Auto Club Speedway in Fontana, Calif.

While it would be easy to wonder what might have been had his gearbox not malfunctioned in Houston, the ever-optimistic Castroneves has no regrets.

"I never felt frustrated," Castroneves said. "Racing is like that, you prepare as much as you can but still, who would’ve figured that the gearbox would break?"

Dixon, who won IndyCar Championships in 2003 and 2008, knows that he is not at the finish line just yet. The grueling MAVTV 500 is a tough race, and Dixon has lost the Championship before because of a poor performance in the final race (teammate Dario Franchitti edged him for the title in 2009 at Homestead).

Dixon says he's treating this weekend like any other, and that the length of the race makes it important to maintain focus.

"It’s a 500 mile race so it’s not a short sprint race," Dixon told ThePostGame. "You’ve got to keep your concentration for three hours and make sure you get to the end."

In order to win his third title Dixon only needs to finish fifth or better, but after what happened to Castroneves in Houston, he knows that some of his fate may be out of his control.

"You’re going to have to have a little bit of luck go your way," Dixon said, "And then you have to be running strong, and that’s what we’ll try to do."