Mario Andretti -- Bernie Ecclestone's Right ... 'F1's Clearly A Man's Sport'

Racing legend Mario Andretti tells TMZ Sports ... he kinda agrees with Bernie Ecclestone when it comes to women in F1 racing -- "it's clearly more of a men's sport."

Ecclestone -- widely considered the most powerful man in racing -- made headlines this week when he said women are too weak to be successful F1 drivers ... and "wouldn't be taken seriously."

So, we called up Andretti -- one of the greatest drivers who's ever lived -- to get his take on the situation. Here's what he told us:

"Bernie doesn’t mince words. He says what he thinks. You could be more delicate about it, but Formula 1 has been in existence for what, 66 years, and we've only seen 5 women try and compete and none have really been successful."

"The bottom line is you can make assertions until the cows come home. Saying women can do it. Bottom line, they have to prove it. You can’t just come out of the woodwork and say ‘I want to be a F1 driver.’ You need to earn your way there."

"Will it happen one day? It’s impossible to predict, but I’d say probably yes. At the same time, someone else might say, if it was going to happen, why hasn’t it happened in 66 years?"

"I think it’s clearly more of a men’s sport. Could there be some women who are competitive? Like with tennis … could Serena Williams compete with men? I think yes, but could she win a major, I don’t know."