Secrets are difficult to keep in the world of auto racing. That’s what makes the news that McLaren and Andretti Autosport have teamed up to campaign a Honda-powered entry in the 101st Indianapolis 500 presented by PennGrade Motor Oil for two-time Formula One world champion Fernando Alonso so stunning.

This was a move that nobody saw coming. Yet it immediately produced waves when announced Wednesday, with the Indianapolis 500 and Alonso trending worldwide on social media.

In terms of the global attention it brings to the Indy 500, this is arguably the biggest driver announcement since 1993, when reigning F1 champion Nigel Mansell (shown above) contested the entire Indy car season for Newman/Haas Racing.

Although this is a one-off – Alonso will miss just one F1 race (the Monaco Grand Prix) while he competes at Indianapolis before returning to the cockpit of his McLaren-Honda for the remainder of the 2017 season – the attention Alonso’s rookie run in an Indy car receives has the potential to be immensely positive for both the Verizon IndyCar Series and F1.

Several other high-profile drivers have contested the Indianapolis 500 since Mansell finished third as a 39-year-old “rookie” in 1993. NASCAR stars Tony Stewart, Kurt Busch, John Andretti and Robby Gordon garnered national attention for attempting to complete an 1,100-mile INDYCAR/NASCAR “double.” Several drivers with recent F1 experience have given Indy a shot, including Rubens Barrichello, Jacques Villeneuve (who won the 1995 Indy 500 before heading to F1 and winning the 1997 title) and Jean Alesi.

But Alonso is on another level, and not just because he’s a current F1 star. He’s a two-time world champion leading the “Most Popular Driver” vote in a survey being run by Motorsport.com.

McLaren brings a high level of attention as well. The respected F1 team has genuine Indy car pedigree, as an entrant and car builder from 1970-79. Mark Donohue drove a McLaren chassis to Team Penske’s first Indianapolis 500 victory in 1972, while Johnny Rutherford added 500 wins in 1974 and ’76 for Team McLaren.

Over the last couple of years, Alonso has publicly expressed his desire to compete at Indianapolis and in the 24 Hours of Le Mans, so his participation at Indy isn’t totally unexpected. But nobody expected it to happen this soon.

“This is a big news day for racing around the world and a red-letter day for INDYCAR and the Indianapolis Motor Speedway,” said Mark Miles, CEO of Hulman & Company, the parent of INDYCAR and Indianapolis Motor Speedway. “From our perspective, Fernando is the gold standard of motorsport drivers around the world.

“I’m really glad to say this is not fake news.”

There is also irony involved in Alonso driving for McLaren in F1 and joining Andretti Autosport for May. In 1993, the opening for Mansell to race Indy cars came when Michael Andretti, then a top Indy car star, announced that he was switching to F1 … with McLaren. The experiment lasted a single year for Andretti, who was back racing Indy cars in 1994.

Now a successful INDYCAR team owner/CEO with four series championships and four Indianapolis 500 victories, Andretti recognizes the star value that Alonso brings to the month of May.

“I can’t tell you how excited I am,” Andretti said. “It’s awesome for everybody involved, including the whole sport of auto racing. It’s such a big story.

“As one of the best, or maybe the best driver in the world, I don’t think he’s going to have a problem adapting,” Andretti continued. “There’s no question in my mind, if we have competitive cars this month of May, Fernando is going to be very competitive.”

That shouldn’t be a problem. Last year, the Andretti Autosport cars were the class of the Indianapolis 500 field. The team finished 1-2 at Indy with Alexander Rossi and Carlos Munoz, not to mention Ryan Hunter-Reay and Townsend Bell ran up front until colliding with each other in pit lane midway through the race.

It’s like when Mansell came to race Indy cars in 1993. The Newman/Haas car he stepped into was coming off a five-win campaign in the hands of Andretti the previous season. Mansell made the most of such a competitive platform, winning his debut at Surfers Paradise, Australia.

However, he crashed heavily in practice for the event at Phoenix Raceway and missed the race. He finished third a week later at the Toyota Grand Prix of Long Beach before making the decision to undergo surgery for the back injuries.

Mansell’s ability to race at Indianapolis was very much in doubt and he missed the first few days of practice. But in his inimitable dramatic style, Mansell fought back to contend strongly in the 1993 race. He led 34 laps but was snookered on a late restart by eventual winner Emerson Fittipaldi and finished third. Mansell went on to earn four more race wins on the way to the remarkable achievement of winning Formula One and Indy car championships in back-to-back seasons.

Mansell’s American adventure brought Indy car racing considerable additional coverage from worldwide media. The IMS media center back then could not accommodate the more than 100 additional credentialed international journalists and required expansion.

Alonso’s participation this year may not have the same level of media impact, but it will still be a significant story around the world.

“This gives the rest of the world another reason to be focused on Indianapolis and on INDYCAR on Memorial Day weekend and really all of May,” said Miles. “We’ve already heard from a number of our international broadcasters, so we think it will make a difference for us at the 101st Indianapolis 500 in terms of global exposure and I think we’ll see there will be long-term benefits.”

Added Doug Boles, the IMS president, “We say every May that the best drivers in the world are competing at the Indianapolis Motor Speedway, and when you add a Fernando Alonso to that field, it’s pretty hard to argue against that statement,”