Jakobsen was jockeying for first place at the end of the Tour of Poland on Wednesday ... when he appeared to be cut off by fellow cyclist Dylan Groenewegen.

What happened next was terrifying ... Jakobsen flipped over some signage lining the raceway and then crashed face-first into a solid barrier.

Jakobsen suffered major injuries in the wreck ... his cycling team announced he had to undergo facial surgery and then be put into a coma.

But, thankfully, team officials say Jakobsen avoided serious spine/neck ailments.

"Fabio had facial surgery during the night," the cycling team said in a statement Thursday. "His situation is stable at the moment and later today the doctors will try to wake Fabio up."

Groenewegen was heavily criticized for his role in the crash ... he was DQ'ed from the race despite finishing first -- and was blasted by Jakobsen's team's GM, who called Groenewegen's end-of-race maneuver "criminal."

For his part, Groenewegen apologized on Twitter, writing, "I hate what happened yesterday. I can't find the words to describe how sorry I am for Fabio and others who have been dropped or hit."

"At the moment, the health of Fabio is the most important thing. I think about him constantly."

Meanwhile, U.S. cycling legend Lance Armstrong sent his best wishes to Jakobsen, saying, "Thoughts and prayers go out to Fabio Jakobsen. Hang in there buddy."