During the Council of Elrond in The Fellowship of the Ring, Gloin explains that a messenger from Sauron came to the Dwarves and asks them to get a Ring from the Hobbits.
"As a small token only of your friendship Sauron asks this," he said: "that you should find this thief," such was his word, "and get from him, willing or no, a little ring, the least of rings, that once he stole. It is but a trifle that Sauron fancies..."
Ultimately the Dwarves refuse to help but had they actually went and found the Ring it seems that they would have quickly discovered that it was much more than a "trifle" and would not have simply handed it over to Sauron.
Assuming that the Dwarf who found it didn't "go Gollum" and vanish (which would just mean that you now have a missing Dwarf instead of a missing Hobbit), this would mean that the Dwarves had the One Ring.
Did Sauron just assume that he could defeat the Dwarves even if they had the Ring?