two things,,,(1) sasuke's main attack then were all lighting types,they all would be useless against kakashi. this wil seriously tilt the scale to kakashis favour. no matter how fast sasuke became or stronger, kakashi will always hav the advantage cause of the experience and know how.(at that stage)
(2) sasuke had the curse seal which only amplfys whatevr was mentioned above,,however kakashi had kamui which again, turn odds to kakashis favour.
kishi may have realised this and hence decided to save the encounter only for after sasuke got the m.sharingan! so conclusion: kakashi wins