Indianapolis Motor Speedway President Doug Boles walks a fine line each May.

Like many longtime Indianapolis 500 fans, Boles reveres the history of the race. As a promoter, he also understands the series needs new blood to expand the fan base and help the 500 keeps its title as the world's largest single-day sporting event.

So as the 2.5-mile oval revs up for its second century of racing, it may the perfect moment to transition from familiar fan favorites to the next generation of winners.

"What makes this place special is the history and the tradition. But what will make it better going into the future are the future winners and a lot of them are young," Boles said last week. "The young drivers are our future."

There are plenty of reasons to catch the new wave.

Alexander Rossi, age 25, is trying to become the first American to win back-to-back 500s since Al Unser in 1970-71.

At age 26, American Josef Newgarden might have his best shot at reaching victory lane. He's coming off a career-best finish of fourth in the points in 2016 and has teamed up with three-time 500 champion Helio Castroneves, defending series champion Simon Pagenaud and 2015 Indy pole winner Will Power on Roger Penske's powerful team. Newgarden already has won at Birmingham this season.

James Hinchcliffe gained some new fans from his offseason appearance on "Dancing With The Stars" but would prefer to complete his comeback from a life-threatening injury two years ago with a win at the Brickyard.

Marco Andretti will again try to break the family's Indy curse. His father and team owner, Michael, led more laps than any other non-winner of the race. The 30-year-old's grandfather, Mario, won once in 29 starts, in 1969.

Graham Rahal has two top-five finishes in nine Indy starts, and a victory would allow the 28-year-old to join Unser and Al Unser Jr. as the only father-son winners of the race. Rahal's father and team owner, Bobby, won in 1986.

Even the 32-year-old Pagenaud, the current points leader, is a relatively new face to IndyCar fans. He's only had five full seasons in the circuit and will try to defend s IndyCar Grand Prix title in Saturday's race.

Boles has his own personal connection with his 25-year-old stepson, Conor Daly, trying to make his fourth straight 500 start.

It's a crucial month for the IndyCar Series, one that could signal a changing of the guard.

"It could be," Boles said. "It's the young drivers that connect you to race fans. But it's a fine line to walk."

Here are some other things to watch this month:

Alonso bump 

Race organizers found the perfect solution to re-create the energy surrounding the 100th race — adding two-time Formula One champion Fernando Alonso to the lineup for No. 101.

Alonso passed his rookie test last week then returned to his native Spain where he is scheduled to race this weekend in F1. When the 2.5-mile oval opens for practice Monday, Alonso, will be back in town, chasing the second jewel in racing's triple crown. He can't wait.

"I remember coming here, I think it was 2004, the first year that I raced here, and, yeah, I was taking pictures of the entrance for the Speedway. You know capital of the world, motorsport," Alonso said. "So it's a special place for motorsport in general. To race here in May on the Indy 500, it feels quite a big thing."

Six pack 

Andretti Autosport is really pushing the limits in Gasoline Alley.

In addition to the team's four full-time drivers — Rossi, Marco Andretti, Ryan Hunter-Reay and Takuma Sato — Michael Andretti has added Alonso and Jack Harvey of Britain to compete in the May 28 500. The biggest challenge may be finding pit crews and spotters for all six cars.

Milestone moments 

Castroneves, of Brazil, will make his eighth attempt at a record-tying fourth 500 win.

His current drought is the longest of Castroneves' Indy career. He won his first two races (2001 and 2002), finished second in his third (2003) and won again in 2009. New Zealand's Scott Dixon, who drives for Chip Ganassi Racing, has quietly moved into fourth on the series' all-time victory list. If he sweeps the two Indy races, he'll tie Michael Andretti for No. 3 in career wins (42).

Ticket sales 

Boles said tickets are selling at the second-best pace the track has had in 20 years, trailing only last year's historic race.

Nobody expects another sellout, but Boles believes the fans who attended last year's centennial race were so impressed that many are coming back.