Danica, Stewart encounter problems

— -- DAYTONA BEACH, Fla. -- Danica Patrick, who won the pole for the Daytona 500 last year, was one of three drivers to have their Hendrick Motorsports engines suffer catastrophic failures in practice Saturday.

Bobby Labonte, driving a second car for HScott Motorsports, was the first using a leased HMS engine to experience trouble in the first practice session of the day. In the second session, the No. 14 Chevrolet of Tony Stewart -- Patrick's teammate at Stewart-Haas Racing -- belched smoke, signaling a failure. Patrick's No. 10 Chevrolet did much the same 10 minutes later. Both Stewart and Patrick said they had no warning.

"It's just a motor. If it was getting ready for the race you would be a little more concerned," Stewart said. "It's just for qualifying. They pay the big check a week from tomorrow, not tomorrow."

Each team will be forced to start from the rear of the field for the Daytona 500. All three cars also will begin their respective Thursday qualifying races from the rear. Pole qualifying is set for 1 p.m. ET on Sunday.

Patrick finished the second practice session in 22nd position. Stewart was 38th.

None of Hendrick Motorsports' drivers, including defending Daytona 500 winner and six-time series champion Jimmie Johnson, suffered such problems. Johnson was the fastest of the HMS contingent at ninth in the second session.

HMS director of track support Scott Maxim surmised problems were in the "bottom" of the engine but would not know for certain until each was dismantled. HMS general manager Doug Duchardt foresaw no problems for the rest of the race weekend, saying the team had "pushed the limit and found the limit."