FORT WORTH, Texas -- For the second consecutive day, steady rain at Texas Motor Speedway wiped out racing -- but Sunday it meant both a Sprint Cup and Nationwide series event were rescheduled to Monday.

At 4:30 p.m. ET Sunday, NASCAR pulled the plug on both events when a rainstorm that began Saturday morning and has continued virtually unabated since then, coupled with an ominous forecast for the evening, left NASCAR unable to dry the track and start the race in a reasonable time.

The front plaguing the area is forecast to begin leaving by midnight local time Sunday. Monday's forecast calls for mostly cloudy skies with a high of 66 degrees and eight-to-10 mph winds from the northeast, with a 20 percent chance of rain. The temperature at the green flag for Monday's Cup Series race is expected to be 56 degrees.

The Samsung Mobile 500, a 334-lap event, now is scheduled to take the green flag at just past noon ET. The only time in TMS's 14-year history that a NASCAR event had to be run on Monday occurred in 2002, when Matt Kenseth won the Samsung/Radio Shack 500 on April 8.

It's the second time in the past three Cup races that an event will be run on a Monday. Three weeks ago at Martinsville Speedway the Goody's Fast Pain Relief 500 was run on Monday and won by Denny Hamlin.

The Nationwide Series' O'Reilly 300, which originally was scheduled to run Saturday afternoon and is the first series race postponed this season, now is scheduled to run after the Cup Series event, with the green tentatively set for about 5 p.m. ET.

NASCAR spokesman Ramsey Poston said five times since 2003 has NASCAR run two national series races at the same facility on the same day: at Richmond in September '08, Fontana in February '08, Daytona in July '07, Charlotte in October '03 and Las Vegas in March '03.

The track, which was only going to allow Cup race ticket holders into the stadium for the Samsung 500 and O'Reilly 300 ticket holders in after the checkered flag Sunday, amended that policy for Monday, when fans holding tickets for either race will be allowed to attend both events.

"It was the fan-friendly thing to do in terms of allowing our fans with either ticket to stay for both races," Texas Motor Speedway president Eddie Gossage said. "The weather has inconvenienced all of them and for those who are able to stay they may as well enjoy 801 miles [501-mile Samsung Mobile 500, 300-mile O'Reilly 300] of NASCAR racing.

"We expect to accommodate all of those ticketholders and are optimistic that they will respect each other and find a nearby seat if they have the identical one."

The Samsung Mobile 500 will be broadcast live by FOX while the O'Reilly 300 will be shown live on ESPN2.

Stewart-Haas Racing Chevrolet driver Ryan Newman is the Cup Series' most recent winner, having scored at Phoenix last weekend.

"It's disappointing not to race [Sunday], but this happens now and then -- we just have to get ready for [Monday]," Newman said. "We have a good car; we are in the top 10 [starts 10th]. I think we're going to be good [Monday], we just have to live with it -- it's part of racing.

"We'll just see how it goes at the start. They will have the competition caution to make changes to the car early if we need to adjust to the green race track. It's the same for everybody so we'll go out and do our best to get a strong finish."

There are 15 drivers scheduled to compete in both races, and Sunday -- for the second consecutive evening -- Nationwide point leader Brad Keselowski, who drives Penske Racing Dodges in both series, is facing a daunting next day.

"It's going to be a long day for me [Monday]," Keselowski said. "Those are tough days that really test you more than as just a competitor, but as an athlete. It's kind of cool -- it makes it an interesting challenge."

Keselowski leads fellow Sprint Cup drivers Carl Edwards by four and Kyle Busch by 15 points in the Nationwide standings and will start 12th in that race and 37th in the Cup race. Keselowski's Penske teammate in the Nationwide Series, Justin Allgaier, in fifth is the first series-only regular in the standings, and he'll start 18th on Monday.

"Hopefully, for some of the regular Nationwide guys, it evens the playing field a little bit -- it's going to be interesting," Keselowski said. "I'm looking forward to it. I think that I've got two good cars. I did a bad job qualifying my Cup car, but my Nationwide car is really fast and my Cup car had some pretty decent speed in practice -- I just need to get it out of it."

Typically, the Nationwide races are held a day before the Cup events, never mind on the same day. Keselowski said racing both in the same day will present a challenge.

"There's a quick adaptation period where you've got to be able to show a certain skill set that's completely different," Keselowski said. "It's like in football -- if you were taking a snap as a wide receiver and then moving over and taking one as running back -- and you've got to do it right away -- it's the next play.

"But it makes it interesting and that's when you see who has the talent to do that -- and the mental strength."

With the top four drivers in the standings being Cup adversaries, Keselowski knows what he faces trying to do a double.

"It's going to be tough," Keselowski said. "[Kevin] Harvick is going to be tough at it. Kyle [Busch] is going to be tough [but] that's cool. Hopefully, we'll get a lot of fans to stick around and watch the Nationwide race [and] hopefully, that's the hidden positive, is that more fans will get to see the Nationwide race, and that'll be cool."

But he's still got to race 801 miles and the race in which he's a bona fide championship contender is the second one, and Keselowski frankly said he was concerned.

"I'm a little nervous about it," Keselowski said. "I wouldn't be lying from the standpoint, to say that I'm very fortunate to be leading the [Nationwide] points [because] I have no room to make a mental error if I want to win the championship -- all year.

"It's going to be very draining to run the Cup race. It gives you an opportunity to make a mental mistake from just being worn down. I'm going to have to work hard to make sure that doesn't happen."

As crewmen prepared to stream out of the garage, Bill Elliott, who dominated the Cup Series' Most Popular Driver award standings for more than a decade from the 1980s through most of the '90s, said he felt worse for the fans that might not see a race this weekend.

"I think a lot of them come for the experience and that's nice -- they come in and [some are] able to go through the garage and see what NASCAR is all about, so it's great from that standpoint," Elliott said. "Now I just hope they get to see a race.

"There's nothing more boring than watching it rain at a race track because the [hauler] doesn't normally have enough food on it if it rains. That's the first thing that goes. You can go on just about every hauler in this garage area when it's raining and everybody is either telling lies or eating -- if not both [laughing]."

The gates will open at 9 a.m. local time. The Sprint Cup and Nationwide series garages, track credential office and TMS ticket office all will open at 8 a.m. local time. The credential office will close at 11 a.m. local time.

Fans looking to purchase tickets for this unique NASCAR doubleheader can do so at the TMS ticket office, starting as low as $91. For those requiring additional ticket information, please contact the TMS ticket office at (817) 215-8500.