Russian league leaders Zenit St Petersburg face a stern test of their title credentials when they face second-placed Spartak Moscow on Sunday.
Zenit, who finished fifth last season, have won all five of their Premier League matches and have a two-point lead at the top over Spartak, who are also unbeaten this season. Rostov sit third, one point further back.
On Thursday, Zenit booked their ticket for the Europa League group stage with a 4-3 aggregate win over Norwegian side Molde and were drawn Friday against French side Bordeaux, Copenhagen and Slavia Prague.
But Zenit head coach Sergei Semak said he hoped his men would draw the right conclusions from the return leg with Molde, which his team lost 2-1.
"The match at Molde showed that Zenit aren't favourites against any opponents," Semak told Russian TV. "And we should never underestimate any team that we will have to face.
"Hopefully my players will learn from the mistakes they made in Molde to avoid them in the upcoming match with Spartak."
Meanwhile, Spartak, who dropped into the Europa League group stage after crashing out of the Champions League with a 3-2 aggregate defeat to Greek club PAOK Salonika, consider the clash with Zenit as a chance to grab the outright lead in the Premier League.
"The good chemistry in the locker room that helped us to win the title two years ago returns little by little," Spartak's site quoted manager Massimo Carrera as saying.
"My men realized that there're no easy games in the Russian league and none of the rivals will gift us points for nothing.
"You always need to fight to get what you deserve. And we're ready to battle to grab the lead on Sunday."
Spartak said Friday Dutch attacking midfielder Quincy Promes, the Russian Premier League's top scorer last season, to join Spanish high-flyers Sevilla on a five-year deal worth around 20 million euros ($23.2 million).
Reigning champions Lokomotiv Moscow, who have won their last two league matches to go fifth, will also have to pass a tough test on Saturday when they visit sixth-placed Krasnodar.
Fyodor Smolov, a major part of Russia's surprising run in this summer's World Cup, last week scored his first goal for Lokomotiv since joining from Krasnodar during the summer break.
He said he was curious about the reception he would get at his former club.
"Though I was a bit nervous as I failed to find the net in the first four matches of the season I knew that my goal drought wouldn't last long," he said.
"I wonder how the crowd in Krasnodar will greet me but in any case I'm going to show my best there. Lokomotiv are the champions and we need to collect maximum points to improve our position in the table."
Lokomotiv face Porto, Schalke 04 and Galatasaray in the Champions League group phase.
Fixtures (all times GMT)
Rostov v Rubin Kazan (1630)
Samara v Anzhi Makhachkala (1100), CSKA Moscow v Ural Yekaterinburg (1330), Krasnodar v Lokomotiv Moscow (1600)
Yenisei Krasnoyarsk v Arsenal Tula (1100), Dynamo Moscow v Orenburg (1330), Zenit St Petersburg v Spartak Moscow (1600), Akhmat Grozny v Ufa (1830)