You might as well be from Russia considering your username, so I'm sorry if the following is obvious for you
It probably will be at the minimum. The hooligans and ultras who fight each other in Russia do so in remote areas because it wouldn't go down well with the OMON special forces.
The Russian government has no problem cracking down on any sort of defiance. In the beginning of the 2000's it was a tradition for protesters to travel to wherever the G8 summit was held, riots in Italy, France, England etc. Once the summit happened in Russia, it was zero. Those who tried to go to a protest there were either sent back from the border, locked down before the planned events or beaten and dispersed in minutes. If i remember right, the Russian sports' minister commented on what went down in Marseilles during the EURO's, he said that WC18 will be the safest ever and I wouldn't be surprised if it was, mostly to prove a point, good for propaganda too.