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72nd minute: Goal. Russia.
Saudi Arabia were under increasing pressure and Smolov's deflected strike was clawed away by keeper Abdullah Al-Mayouf when play continued after an offside had been missed.
The host nation had the momentum towards the 20th minute and were unlucky not to have found the second goal through their high press.
Substitute Denis Cheryshev scored twice, with Yuri Gazinsky, Artem Dzyuba and Aleksandr Golovin also on target at a delirious Luzhniki Stadium.
Alan Dzagoev left the game after just 23 minutes as he suffered a hamstring injury, but super sub Cheryshev ensured that the home side stretched their lead going into the interval.
Russian Federation and Saudi Arabia are the two lowest-ranked teams at the tournament by some distance. With the goal at his mercy Cheryshev proceeded to blast the ball into the roof of the net from about 12 yards for his first goal for his country. Denis Cheryshev enters the match.
Stats: Dzyuba's goal (89 seconds), is the quickest goal by a substitute at a World Cup tournament since Marcin Zewlakow scored for Poland vs U.S. in 2002. The match is the first game of the tournament.
This week Putin had said Russian Federation - going into the tournament ranked 70th in the world, three places below Saudi Arabia - would "fight until the end", but, in this match at least, a poor Saudi Arabia proved to be obliging opponents as they gave the hosts freedom in possession and, crucially, the opposition box.
When: Thursday, June 14 at 8 a.m.