It’s down to the final four in the #ChampsOfThe500 bracket challenge, and four is a most appropriate number for the voting contest on the Indianapolis Motor Speedway website.

The only four-time winners in Indianapolis 500 Mile Race history – A.J. Foyt, Al Unser and Rick Mears – fill three of the semifinal spots in the challenge. The remaining semifinalist is Helio Castroneves – who will chase his fourth victory at the “Greatest Spectacle in Racing” later this month.

Sixteen legendary Indianapolis 500 winners were initially selected to square off in the digital voting platform running through May 23, leading to the historic 100th Running of the Indianapolis 500 presented by PennGrade Motor Oil on May 29. Fans can vote for their #ChampsOfThe500 once an hour while each pairing is open by visiting ims.com/champsofthe500. 

Fans also are encouraged to tout their votes by using the hashtag #ChampsOfThe500 in Facebook and Twitter posts. The voting contest runs in conjunction with Legends Day Honoring Champions of the 500 presented by Firestone at Indianapolis Motor Speedway on May 28.

In quarterfinal round voting that concluded Sunday, Unser defeated three-time Indy 500 winner Johnny Rutherford by a margin of 71 percent to 29 percent, and Mears defeated 1969 Indy winner Mario Andretti, 69 percent to 31 percent. In earlier quarterfinal voting, Foyt topped Bill Vukovich and Castroneves bested Bobby Unser.

Semifinal voting for both pairings began at noon ET today and continues through noon ET Friday. The two survivors advance to the championship round of voting that begins May 16. Show your Indianapolis 500 pride and vote hourly for your #ChampsOfThe500.

#ChampsOfThe500 Semifinal Pairings:

May 9-13: A.J. Foyt vs. Helio Castroneves; Al Unser vs. Rick Mears

Note: Voting begins and ends at noon ET on the designated days; drivers receiving the most votes in each pairing advance to the championship round. Vote at ims.com/champsofthe500.