Like I've said before, chakra chains are bullshit, since she's only shown use of them while having a raging hard on for Sasuke and freaking out over his death. And Karin has been almost completely useless throughout the series, showing just about 0 feats.
Sakura takes it low difficulty.
Also how in the world do people even like Karin as a character? She's one of the worst characters I've EVER seen in anything ever. She's way more of a horrible character than Sakura, yet Sakura gets all the hate. I don't get it at all.