An accident in final practice at Michigan International Speedway has sent Kyle Busch to his backup car for Sunday afternoon's Pure Michigan 400 NASCAR Sprint Cup Series race.

CLICK: Full Saturday practice session results from Michigan International Speedway.

That means Busch will now have to start from the back of the field, rather than the sixth place in which he qualified on Friday.

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All four Joe Gibbs Racing cars had landed themselves positions on the front three rows of the grid for the start of tomorrow's race, with Matt Kenseth clinching pole position and Denny Hamlin joining him on the front row in second. The newest addition to the JGR line-up, Carl Edwards, will start from third.

But Busch will now be right down the other end of the grid for the green flag, after damaging his race car just four minutes into Saturday's third and final practice session on the two-mile oval.

Busch was running all my himself when the back of the ?18 snapped loose running through turn 4. The car then slid through the in-field grass, sustaining major damage to the nose and front end in the process.

Everything was fine. I was just trying to run around there and maintain speed," the JGR driver told reporters after being released from the in-field care centre. "I got a little bit free off 4. It started stepping out like it did here in the spring. I over-corrected and hit the wall so this time around I just kind of made it keep rotating and head down toward the infield.

Despite managing to keep the car off heavy contact with the wall itself, the run through the grass did too much damage for the crew to repair. Busch, no fan of grass at race tracks, was cutting in his sarcastic remarks: "I think at all these tracks we need more grass. I think more grass would be beneficial," he said, adding: "I think we should have more grass and it should be taller."

Busch was fourth-fastest in the original car when he spun out. He was able to get the backup out on track and work on the set-up in the time remaining and ended the 55-minute session as the ninth-fastest driver.

Although Busch has four wins to his name in 2015 - all of them coming within the last month and a half - he must still finish in the top 30 to be eligible to go forward into the Chase allowing him to compete for this year's championship.

Second place last weekend at Watkins Glen means he is now in that position - but only just. Busch can't afford even a single poor result between now at the Chase cut-off which takes place after September 12 following races at Michigan, Bristol, Darlington and Richmond.

The big concern for Busch starting so far back isn't making up all the lost positions - the pace showed by all four JGR cars on Friday proved that shouldn't take very long - but the risk of getting caught up in mid-field accidents along the way that could send him into premature retirement.

Trying to look on the bright side, Busch pointed out that at least he had now learned what not to do with the new high-drag rules package being used at Michigan for the first time this weekend.

"We just learned about how the draft was and what kind of instances you could try to put yourself in and what kind of instances you didn't want to be in," he said. "Now that we have to start in the back, it's a good thing we did that. It's a good exercise and we'll just have to adjust our car for being in the back of the field."

Furniture Row Racing's Martin Truex Jr. was the fastest man in the session, clocking in at 37.553s (191.729mph) just ahead of Penske's Joey Logano. Just as he was in qualifying, Edwards was third fastest while Ganassi's Kyle Larson was fourth ahead of Richard Childress Racing's Austin Dillon who was the fastest non-JGR car in Friday's qualifying.

However, Dillon's car was reported as suffering an engine issue at the end of the session, leaving the crew working anxiously on the #3 to see whether it can be fixed in time for the race or if an replacement unit will have to be installed - which could see Dillon joining Busch at the back.

"We really don't have a really good explanation yet," said Dillon, immediately after the end of practice. "We think it is something to do with fuelling. It is showing on the EFI [electronic fuel injection] that it wasn't getting enough fuel. We will see if it is a fuelling issue, if not, if it's a bigger issue we will change the motor for Sunday. And have a fresh bullet going into the race."

In the early morning practice session, Stewart-Haas Racing's Kevin Harvick set the fastest time of the day with a time of 36.964s (194.784mph), seven hundredths faster than pole sitter Kenseth. Larson was third quickest on this occasion and Kyle Busch had been fourth fastest. Jimmie Johnson founded out the top five.

The Pure Michigan 400 will get the green flag at 2.30pm ET on Sunday afternoon (7.30pm BST).

Saturday will also see the NASCAR Camping World Truck Series in action at Michigan, while over at Mid-Ohio Sports Car Course the Xfinity Series will be in action competing on the permanent road course later today.

See full Saturday practice session results from Michigan International Speedway.