IMHO I see gaara winning this battle. I will explain my reasonings below.
1) Gaara is a long range fighter. Most of sasukes techniques are useful in close range and therefore puts him in a disadvantage.
2) Gaaras techniques involve not only the sand in his gourd, but the sand in the environment as well, although his control over it is not as quick or precise, meaning that he has the advantage of the terrain itself.
3) While sasuke may be quick, gaara has gained even greater control over his sand since the fight with deidara, and hence the speed of his sand has increased even more so.
Again, this is just my unbiased opinion. I don't hate sasuke or any other characters for that matter, but I believe that he won't win this fight. Feel free to make your own arguements against my ideas.