Martin Truex Jr. set the pace in the first of Saturday's two practices for the MyAFibRisk.com 400 at Chicagoland Speedway.
Truex, who enters the first race of the Chase for the NASCAR Sprint Cup as the No. 10 seed, had a best lap of 183.312 miles per hour in the No. 78 Furniture Row Racing Chevrolet, tops in the 43-car field.
In the first 15 races of the year, Truex had 14 top 10s before slumping a little over the summer.
"I feel confident that we'll hit our stride (in the Chase)," said Truex's crew chief Cole Pearn. "We've had really good speed over the summer, it's just that circumstances have not necessarily played out."
After being dreadfully slow during Friday's lone practice when he was only 30th fastest, Denny Hamlin jumped up to second best in the No. 11 Joe Gibbs Racing Toyota, running 182.389 mph in Saturday's opening practice.
Hamlin said the competition in this year's Chase might prove especially tough.
"You can't rely on other people having bad weeks and a lot of people had bad weeks in the Chase (last year)," said Hamlin. "You can't rely on that and you have to go out and perform really, really well and I think this year will be harder to move on especially in the earlier rounds than what it was last year."
Four-time Sprint Cup Series champion Jeff Gordon wound up third in practice, followed by Austin Dillon. Brad Keselowski, winner of two of the past three races at Chicagoland Speedway, completed the top five.
The final Happy Hour round of practice in advance of Sunday's race is set for 4:30 p.m. ET.
For complete results from Saturday's second overall practice for the myAFibRisk.com 400, click here.