Rubin showed good football in the match against Kuban. Zenit have been kicked out of the Champions League, losing to Benfica. But this does not cancel the fact that Zenit should now fight in the league. There is also a semi-final of the Russian Cup ahead. And now there is a chance to get within 6 points from the leaders. Given future personal matches, 6 points is not that much. But first, they need to win the game against Rubin.
I expect goals from Zenit here. Rubin, of course, are a skilled team, but Zenit must start scoring sooner or later. I suggest picking Zenit total over 1.5 goals. The odds are good. The turf at the Petrovsky stadium is good. We cannot say that Zenit are very good, too. But they ought to show their best game, to reach good form, to get angry.