Martin Truex Jr. is not sure what he must do to keep up with the powerhouse teams of Sprint Cup or how long he'll continue to face such questions.

Truex Jr. led the most laps at Kansas, Charlotte and Dover yet didn't win any of them. He finally broke through this past Sunday for victory at Pocono, ending a nearly two-year drought and all but locking him into NASCAR's championship chase.

Still, his first question at Darlington Raceway was what he was missing to consistently outrun Jimmie Johnson and Kevin Harvick. A surprised Truex answered back, "We just outran them."

Truex worked Wednesday to stay up front, taking part in a test session at Darlington Raceway before moving on to Michigan for this weekend's race for another chance to finish near the top. For Truex, the Pocono win was long overdue with how well he has performed this season.

He's had 13 top-10 finishes in 14 races this year and sits second in points, a prime position for the NASCAR playoffs even without the satisfying victory last week.

"Honestly, I think we've got everything it takes to do what we need to do," Truex said. "We've got to keep working hard. We've got a lot of racing left before the chase even starts."

That's why Truex was back running laps at the track "Too Tough To Tame," marking the first time Sprint Cup competitors have run at Darlington since the Southern 500 in April 2014. This year's event was shuffled back to Labor Day weekend after running in the spring the previous 10 seasons.

NASCAR had run the Southern 500 on Labor Day weekend from 1950 through 2003.

"The weather feels normal, that's for sure," said Trent Owens, crew chief for Aric Almirola of Richard Petty Motorsports.

Count on it being hot and slippery when the racers return in three months.

Clint Bowyer took part in a Goodyear Tire test session here Tuesday and stuck around for the open test. The veteran driver was practically giddy that Darlington was back to its gnarly, tire-chewing self after watching his tires wear down quickly on long test runs.

Darlington lost some of its fierceness after a 2008 surface repaving. But after what Bowyer's seen during the two test days, he's confident competitors will get the same, old, point the car and hope it sticks feeling going into turns one and two this September.

"This old place, let me tell you, it's back to the old Darlington of slipping and sliding around," he said. "It's back the way it needs to be to put on good racing."

Joining Truex and Bowyer at Wednesday's tests were Daytona 500 winner Joey Logano of Penske Racing, six-time Sprint Cup champion Jimmie Johnson of Hendrick Motorsports, Greg Biffle of Roush Fenway Racing, Kyle Busch of Joe Gibbs Racing and Kurt Busch of Stewart-Haas Racing.

"A lot of good cars here so there's a lot of good comparisons and you know how you stack up against the competition," Bowyer said.

Aric Almirola said the work here will benefit his Richard Petty Motorsports team at Darlington and also in the rest of the remaining races in the regular season. The test "gives us a chance to run through different set ups and different ideas," he said.

One thing is certain: The Southern 500 move promises to make a fiery weekend — remember Harvick throwing a punch into Kyle Busch's car in 2011? — even more competitive as the next-to-last race before NASCAR's championship chase.

Tempers routinely sparked at Darlington on Mother's Day weekend, so imagine what might happen with playoff chances on the line.

Almirola already sees it unfolding.

"Darlington always brings out the best is us drivers as far as tempers flaring," he said. "It's such a challenging race track. It's a draining race track, not just physically, but mentally just trying to keep that focus."