Kyle Busch had just won a NASCAR Xfinity race — his first time back on that series after being injured in a February accident — when he confidently eyed the next day's Sprint Cup event.

"This is only a preliminary to what we have to do for Sunday," he said.

The next day, he crashed his car into the wall and finished last.

It's been a turbulent year for both of the Busch brothers. Less than four months ago, it was fair to wonder if either of them would be a factor in stock-car racing this season, but they both came away with victories last weekend at Michigan International Speedway. A day after Kyle won the Xfinity race, Kurt Busch took the rain-shortened Cup race.

The question now is whether either of these two big-name drivers can contend for a title as the season winds down.

"Any time you win, it comes with a basket full of goodies," Kurt Busch said Sunday. "More of what is the unknown is what comes from this, and that is the pep in the step of the crew members, the genuine chemistry and the feel on the shop floor."

With two victories this season, Kurt Busch has little to worry about in terms of making the Chase for the Sprint Cup championship. The same can't be said for Kyle, who has started only four Cup races this year and won none of them.

After a ninth-place finish at Pocono, he came to Michigan with high hopes and won the Xfinity race Saturday.

"Whether it was the Cup side or the Xfinity side, I certainly knew that we would win some races this year," Kyle Busch said.

But the race Sunday was a lackluster one — both for Kyle Busch and the viewing public. It was halted four times because of rain, and shortly after one restart, Busch crashed his No. 18 Toyota.

It was hard to criticize him too much given the conditions, but the 43rd-place finish left him 39th in the points standings. He not only needs to win a race to put himself in position for the Chase, he also needs to be in the top 30 in the standings.

If he does miss the Chase, he'd certainly have an excuse this year. His February crash at Daytona left him with a broken right leg and left foot.

Kurt Busch missed the first three Cup races this season because he was suspended amid allegations of domestic assault on an ex-girlfriend. When the decision came from authorities to not charge Busch with a crime, he was reinstated by NASCAR.

He is 11th in the standings despite missing those three races. The next step is to show he can compete with the very best drivers on a consistent basis — 11 years after he won the Cup title with Roush Fenway Racing.

Kurt Busch, now with Stewart-Haas Racing, had to use his backup car in Sunday's race after a mishap at practice two days earlier. He won anyway in the No. 41 Chevrolet, but that's obviously the type of mistake that can cost a driver.

"I talked to him about that a little bit — 'You're a great race car driver, you shouldn't be doing things like that,'" owner Gene Haas said. "I guess he drives that car within a millimeter of the wall all the time."

There was nothing particularly erratic about Kurt Busch's performance Sunday. Sure, there was a fluky element to the win, since he led for only six of 138 laps in a race shortened from 200. But he's only finished outside the top 15 once all season.

As much drama as he's been involved in during his career, his performance of late has been steady.

"I think the run for the championship, that's what it's all about," Haas said. "I'm absolutely clear that I think Kurt Busch has the ability to win another Cup for us and for Stewart-Haas Racing."