How did Negi Springfield get the scar on his left cheek?

Negi surely got his scar (on the left cheek) during the Mahora Tournament.

It isn't quite clear whom it was among Takamichi Takahata or Setsuna Sakurazaki caused the scar. Whether it was because of Takamichi's kanka punch grazing his cheek, on ch 98 pg 5, or because of Setsuna's claw attack, on ch 115 pg 18. Both attacks were on the same cheek, and both have enough proximity to the scar left.

However, I believe that this scar was cause by Setsuna as it was mentioned on ch 225 pg 11.

See the related links for the pages that his scar is mentioned on.