The 28-year-old was heading around a turn at a high rate of speed during preparation for this weekend's Dutch TT in Assen ... when all of a sudden his bike bucked him.

Footage from the track is absolutely terrifying ... you can see Marquez was thrown feet into the air while his motorcycle skidded across the pavement underneath him.

Marquez eventually crash-landed into some gravel ... where he rolled several times before sliding to a stop.

Somehow, though, he said he avoided any sort of serious injury.

"I have to say I feel lucky to escape in a good condition overall, these kinds of crashes can be very hard and very dangerous," Marquez told media members afterward.

"It’s painful, but nothing is wrong. It was a strange crash because I didn’t think that I was over the limit and I was riding like I was in the morning."

Marquez continued, "In this corner we rely on the traction control a lot, but it wasn’t there, and when I shifted the rear started sliding and then I fell."

If this all sounds familiar for Marquez ... it's because it is -- remember just last year in July, he broke his arm in a similar accident in Spain.

In that crash, Marquez was thrown from his bike in nearly an identical fashion.