INDIANAPOLIS (AP) The Andrettis have split up.

Michael and Marco Andretti will not work together during this year's Indianapolis 500, and it's unclear if or when they might get back together for race day calls. Michael is now calling races for Ryan Hunter-Reay, who has won three times in the IndyCar Series, while Kyle Moyer is reunited with Marco.

"Dad has now moved to work on Ryan's car, but before that he was on mine and he got so hands-on that my engineer Allen McDonald and I had to literally justify every change we were making to the car," Marco wrote in a blog post that appeared online Saturday.

Team spokeswoman Ryann Rigsby said Sunday the change was actually made before the race in Brazil. Andretti finished 14th in that race, while Hunter-Reay finished second.

Michael Andretti declined comment on the move. Marco went into an engineering meeting following Sunday's practice and was not immediately available for comment, either.

Moyer made the calls for Danica Patrick in 2008 before moving to Marco's team in 2009. With Moyer, Patrick produced three top-five finishes and 10 top-10s. Marco had two top fives and 11 top-10s with Moyer in '09.

While Marco first four races in 2012 have been frustrating with finishes of 14th, 11th, 25th and 14th, Hunter-Reay has finished in the top-six three times and is fourth in points.

But Marco believes a strong performance at Indy could turn the whole season around. He has finished second, third and third in his three even-year races at the 2.5-mile Brickyard, though he was only 19th on Sunday's speed chart at 217.706 mph.

"We stuck to the single-car runs in the No. 26, so we didn't show the same speed of the guys who were taking advantage of tow from other cars," he said. "But everyone learned a lot from each other."

Young Guns

Indianapolis' young drivers certainly made a splash this weekend.

On Saturday, three American 20-somethings - Josef Newgarden, JR Hildebrand and Bryan Clauson - topped the speed charts.

On Sunday, Colombian Sebastian Saavedra joined the club. The 21-year-old posted the best speed on the second full day of practice at Indy with a tow-aided 221.526 mph. Clauson and Newgarden, teammates with Sarah Fisher Hartman Racing, were second and third.

The simple explanation is it's all about strategy.

"We're five cars and all of us have homework to do every day," Saavedra said, referring to his IndyCar team, Andretti Autosport. "We have things to try, and we sit down together to see what works, to see what we need for the next day, but everything is a big strategy."

It's the same for other teams.

Most spent the first two days shaking down their cars. Target Chip Ganassi Racing even used the backups in Saturday's practice. Roger Penske's three drivers are still getting a feel for how the new cars will react on the first oval race of the season.

As for the young guns, they're leading the pack right now.

"If you had told me that we were going to come out here the first two days and top the speed charts, I would have told you that you were crazy," the 22-year-old Clauson said. "I'm a rookie, so I don't know what to expect for the rest of the month, but I'm really confident."

Working Mother's Day

Team owner Sarah Fisher celebrated her first Mother's Day at her favorite place - Indianapolis Motor Speedway.

It was a fitting choice.

Fisher was the first woman to win a pole in IndyCar history, the youngest female to start in the 500 and is still the fastest woman qualifier for the 500. But after nine career Indy starts, Fisher jumped out of the cockpit last season to start a family and became a full-time owner.

In October, just weeks after her baby girl was born, Ed Carpenter gave Fisher her first win as an owner at Kentucky. On Sunday, mother and daughter were back at the track, together.

"It's nice," Fisher said. "It was nice to be able to sit with her a little bit in the (motor) coach before we had to get busy with work."

Special Helmet

Hunter-Reay is wearing a new helmet this month, one to honor the memory of the late Dan Wheldon.

The helmet includes an image of Wheldon following last year's victory on one side and the champion's traditional Borg-Warner Trophy on the other.

Wheldon won his second Indy 500 last year, passing race leader JR Hildebrand in the front straightaway after Hildebrand tried to pass a slower car on the high side of the final turn on the last lap. Hildebrand's No. 4 car skidded across the yard of bricks in second place.

Wheldon, who conducted most of the testing in the new Indy cars, was killed in an October crash at Las Vegas.

"It's a pretty cool helmet, and it will be special to me for many years to come," Hunter-Reay said. "Dan is the champion. He's the champion of the race and a great ambassador for our sport. He's a legend. We all miss him. He deserves every bit to a part of the festivities this year."

PIT STOPS: Wade Cunningham completed the third and final phase of his rookie test Sunday. Former Formula One driver Jean Alesi and Katherine Legge are the only rookies that have not passed their rookie tests. ... Newgarden is trying to become the first Tennessee driver to ever start the Indy 500. ... The Alley Cats have added a new sign to their regular spot between pit lane and the garage area as a tribute to Wheldon. ... For the first time, the track has put up advertising signs on the walls in the third and fourth turns.

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