The 44-year-old team owner gave the Indianapolis 500 one more try last year so he could be in son Marco's rookie race, just like his own father, Mario, had done with him 22 years earlier.
One more race, he thought, and he would head back to the garage for good.
Didn't quite work out that way.
Despite a three-year layoff, Andretti was not only competitive, he darn near won.
With three laps to go, Andretti was leading the race that had provided so much bad luck and heartbreak to his family since Mario's victory in 1969. The next lap, Marco passed Michael for the lead and appeared headed for victory.
Then, in an incredible pass coming down the final straightaway on the final lap, Sam Hornish Jr. went around Marco Andretti and won by .0635 seconds, the second-closest finish in Indianapolis 500 history - and another Andretti disappointment.
"I still think about it. It still ticks me off," Michael Andretti said. "I know it does the same thing with Marco. ... As exciting and everything as it was, there's still that pit in your stomach when you think about it. I'm not sure that will ever go away unless one of us wins."
Michael Andretti, who wound up behind Hornish and Marco Andretti, said the close finish convinced him to come back this year as the fifth driver for Andretti Green, joining his son, Tony Kanaan, Danica Patrick and Dario Franchitti.
"I guess after coming so close and sitting back and thinking about it, and looking at things we're going to do with the team and hopefully get the cars more competitive than they were last year, I thought, â€˜You know, let's give it one more shot,'" he said.
Because he hasn't driven in a race since last year's Indy 500, Michael Andretti completed a refresher test during the weekend's rookie program and was ready for the start of full practice Tuesday.
"It was great to get back out there, get a few laps in and get all of the cobwebs out," he said.
"The initial feeling comes right back to you, because you know you can get up to speed. We know the car and the setup and everything, but getting the actual comfort to where you can just lay your head back and relax, it takes a few laps."
Still, he drove only a dozen or so laps Sunday and had the fastest speed of the day at 219.871 mph. He drove another 43 laps Monday and, with Marco watching from the pits, again had the quickest speed at 221.579.
He topped 222 mph on Tuesday, but he had plenty of company as all the other top contenders got on the track for the first time.
Dan Wheldon, the 2005 winner and the IRL series leader with two wins in four races this season, was the fastest at 225.074 mph. Two-time winner Helio Castroneves, Tomas Scheckter, Scott Dixon, Kanaan and Patrick were all above 224.
Marco Andretti and Hornish were among another half-dozen who topped 223 mph, and former winner Buddy Rice joined Michael Andretti above 222.
Jon Herb had the first crash of practice, spinning into the second-turn wall and across the track to the infield grass. He was not injured.
Practice continues through Friday, with the first of four qualifying days for the May 27 race set for Saturday.