For this game, you need 10 ranked wins in a row. Now, a few points :
* Despite disconnects counting on your stats, they do not count towards this achievement. However, they do not halt its progress either. Its as if the match never happened.
* It doesn't not have to be in one play session
I can confirm this, as when I earnt the achievement it went like this :
Won 5 in a row.
6th person disconnected as I did fatality (stats now show 6 streak)
Won 4 in a row (stats now show 10 streak)
11th person disconnected (stats show 11 streak)
So the achievement didn't pop until after I had hit 10 wins without any disconnects.
My cheevo popped at 12 streak, which proves the 2 d/c's didn't count.
So, if someone quits out on you, unfortunately it won't count for the achievement.
*A general tip I'd like to give, is not to spam moves. Not because its cheap, but because a semi decent player will nail you. Block is your friend. If your lucky, you'll run into spammers. Let them spam Smoke/Scorpions teleport punch, let them spam Kabals dash....just block, and take a free uppercut. Being defensive is far more productive than spamming attacks in my opinion.
The great thing about this Mortal Kombat, is you can really pick your spots. Wait for an opening before you attack. Know the opponents character, and within 10 seconds of the first round starting you will know what kind of player he is.
This achievement may prove tricky, because every now and again us average gamers will run into a master, and that usually spells trouble!