They fought once in the '70s (a fight that was partly staged), and never again since, until now.
It's quite significant in terms of Shang-Chi's rep, because there's been a growing school of thought that Danny has gotten better than Shang in recent decades, due to the fact that he's continued to get pushed against mainstream Marvel characters (fighting many more superhumans, for example), whereas Shang's solo titles have tended to operate in their own little world, and Shang has appeared much less frequently in recent decades, clocking up fewer good showings as a result. Contrary to the above school of thought, I always expected that if they fought again now, they'd still be portrayed as equals/peers (as they were in the '70s), and this seems to confirm that.
Now, when oh when will we finally see Shang throw down with Daredevil...? That's one Marvel MA match-up that's LONG overdue.
How would either fare against likes of Bats, or Cap?