Tony Stewart considered himself as an underdog to win this year's Chase for the Sprint Cup championship. After taking the checkered flag for the first playoff race on Monday at Chicagoland Speedway, his thinking has changed...somewhat.

Stewart had generally been one of the hottest drivers during the summer months, but that wasn't the case this season until recently when he finished third at Atlanta and then seventh at Richmond before his Chicagoland win.

With Fall beginning on Friday, Stewart is on a roll and has emerged as a championship contender, whether or not he agrees with it.

"We've had a miserable year, but the last three weeks, we have really started coming into it," Stewart said after claiming his first win of the season. "We had a really good run in Atlanta, good solid run last week at Richmond and then to come out this weekend, I didn't honestly know going into the race. I don't think [crew chief] Darian [Grubb] and I thought that we had as good a car as we thought we needed to win [Monday]. But it didn't take long in the race to figure out that we were pretty solid."

While several Chase contenders ran out of gas during the final laps and ended up with disappointing finishes at Chicagoland, Stewart conserved enough fuel to cross the finish line first, almost a full second ahead of second-place runner Kevin Harvick.

Stewart notched his 40th career victory, which placed him in a tie with Mark Martin for 16th on the all-time race winners list in NASCAR's premier series. It was his first win since October 2010 at Fontana, CA (32 races ago). The 40- year-old Stewart said he doesn't want to wait another year for his next victory.

"I hope it doesn't mean that I have to wait until I'm 41 to get another win, because that's going to suck, having to wait and get one a year," he jokingly noted.

He has scored at least one victory in each of his 13 seasons so far in Sprint Cup.

Stewart's latest win was no fluke. Despite a 26th-starting position, Stewart had one of the fastest cars throughout the 400-mile race, and his crew gave him solid pit stops.

"We come in every week trying to be the fastest race car and doing everything we can to get the best finish we can get," Grubb said. "[Monday] it all worked out in our favor, and we're going to try to do the same thing next week. We don't get a chance to celebrate too much. We have to be in the shop getting ready for New Hampshire. We have a lot of hard work ahead of us, nine more weeks to keep doing what we're doing."

Stewart moved up to second in the Chase standings, as he trails new leader Harvick by just seven points.

Can Stewart keep the momentum going?

"We've still got nine hard weeks to go, and we have some tracks that have been a struggle this year," he said. "So we've got a long way to go, but this gets us off to the right start."

New Hampshire is the next stop on the Chase tour. Two months ago, Stewart and his teammate, Ryan Newman, bolstered their playoff hopes at that one-mile track, where Newman and Stewart qualified and finished 1-2, respectively.

Stewart-Haas Racing's performance at New Hampshire in July came as a surprise to many. Stewart made a key personnel change in his organization the month prior, with competition director Bobby Hutchens being released from the team, while Matt Borland took over the role in the interim.

Stewart began the 10-race Chase in the ninth seed. Last Thursday, the two-time Sprint Cup championship said seven of the 12 drivers in the Chase had a shot at winning the title. He didn't consider himself as one of the them. In fact, Stewart said he had the least amount of confidence heading into this Chase than any other one of his previous six appearances in the playoffs.

Some are now wondering if he's sandbagging it just a bit.

"Counting Tony Stewart out, that's pretty funny that he counts himself out," Harvick said after the Chicagoland race. "He's won a ton of races to start off the Chase like he did [Monday]. They have the notes and teammates and things to lean on at Hendrick Motorsports and Ryan and all the stuff they have to lean on. There's no way they're going to be totally out to lunch. So I think that's yet to be seen. He ran strong all day and drove from the back to the front and led the race and won the race."

Maybe Stewart has been deceiving, but one thing is for sure. He's got everybody thinking that he has a good shot at winning his third championship.

So much for being an underdog.