McLaren Formula One boss Zak Brown is 'barking mad' to let Fernando Alonso race the Indianapolis 500 with so little experience of ovals, Red Bull team principal Christian Horner said on Friday.
McLaren announced earlier in the week that the Spaniard, a double world champion, would miss the May 28 Monaco Grand Prix to compete at The Brickyard in the biggest event in U.S. open-wheel racing.
The switch has been made easier by McLaren's lack of competitiveness in Formula One, with the once-great team currently last in the championship without a point after two races and Alonso clearly frustrated with the situation.
"Look, it's a difficult one for Fernando, he's having a tough time," Horner, smiling, told reporters at the Bahrain Grand Prix.
"Zak's got the problem of a depressed driver on his hands, he's trying to keep him motivated and he's come up with this idea to send him to Indianapolis. He must be barking mad, it's the nuttiest race I've ever seen.
"No testing, he's just going to jump in the car...Turn One there is a proper turn as well, it's not just easy flat all the way round. So I think he needs to see a psychiatrist, personally."
Indy Car racing has a reputation as a considerably riskier series than Formula One, with cars running nose-to-tail at around 240 mph.
Last year's race was won by a rookie, however, former F1 driver Alexander Rossi with the same Andretti Autosport team that will run Alonso's car.
Horner said he would not have let his drivers, Dutch teenager Max Verstappen and Australian Daniel Ricciardo, race in the event.
"I think if a driver commits to a team it's like disappearing with another girlfriend half way through the year, it doesn't seem like the right thing to do," he said.
Brown, an American former racer and marketing expert who was appointed McLaren's executive director last year, defended himself as he sat next to Horner in a post-practice news conference.
"Fernando's not scared," he said. "He's going to get some testing in. He is studying Indianapolis, it's obviously going to be a challenge but he wants a challenge.
"I think he'll have a car capable of running at the front, and I think he will be extremely prepared. I think he's going to put on a good show and he's very smart. And that's what you need to be around Indianapolis.
"I think it's going to be good, everyone's going to be watching."