Pre - Adamantium Wolverine and Sabertooth have practically the same powers and abilities, with Wolverine having a slightly better healing factor. So, in a fight between them, the outcome would come down to brute strength and fighting ability.
Wolverine stands at 5'3" and weighs 195 pounds without Adamantium as shown on Wolverine's data from the official Marvel website. Sabretooth, on the other hand, towers over him at a height of 6'6" with a weight of 275 pounds as shown on Sabretooth's data from the Marvel website. His physical attributes itself put him at a huge advantage over Wolverine.
The height, however, can be overcome by fighting ability. With proper training, Wolverine could have still won at his disadvantaged height. But here, at this point in the movie, both Sabretooth and Wolverine have minimal professional training. Moreover, Sabretooth proves to have more animal-like instincts and a raw bloodthirst, that may help him make the quick decisions necessary in a fight. Hence, without the Adamantium it can be speculated that Wolverine could not have beaten Sabretooth and shows Sabretooth's physical superiority over Wolverine.