Samuel Eto'o and Lacina Traore scored as big-spending Anzhi Makhachkala beat Volga Nizhny Novgorod 2-1 to go top in Russia on Sunday after CSKA Moscow had slumped 2-0 at city rivals Dynamo.
The club from the republic of Dagestan capital have 23 points from 10 matches and are two points ahead of second-placed CSKA while Lokomotiv Moscow are third with 20 points.
Cameroon star Eto'o, the Anzhi skipper, fired home in first-half injury time to put his team in front after being set up by Traore's pass.
Volga pulled level through midfielder Ilya Maximov, who beat Anzhi goalkeeper Yevgeny Pomazan with a 16-metre shot just before the one-hour mark.
But Ivory Coast striker Traore scored the winning goal just three minutes later on the counter-attack, sending the ball into the net from close range off an Eto'o pass.
"After CSKA were defeated we intended to win today. Volga are dangerous opponents made up of skilled and experienced footballers," said Anzhi head coach Guus Hiddink.
"But we managed to take the lead in such a strong and difficult championship as the Russian Premier League. It's a very important event in the history of the club."
CSKA, who had won six consecutive matches, fell behind when Hungarian midfielder Balazs Dzsudzsak put Dynamo ahead in the 38th minute, firing the ball into the net from close range after a mix-up in the Red Army defence.
Dynamo forward Alexander Kokorin added the second goal with a powerful 20-metre shot in the 51st minute.
CSKA's miserable afternoon was completed in the 58th minute when Russian international midfielder Alan Dzagoev was shown a straight red card for a foul on Dynamo's Australian right back Luke Wilkshire.
"We understood that we were playing against the league leaders who are very impressive when they are in control of the ball," said Dynamo manager Dan Petrescu.
"We tried to give CSKA no space and it paid off as we scored twice on counter-attacks.
"Dynamo are still in danger after a disastrous start to the season but our hard work at training has allowed the team to achieve some progress and win our two last matches."
In Sunday's other match, two-time champions Rubin Kazan beat hosts Rostov 4-0.
Rubin's Venezuelan forward Jose Rondon scored a double in the first half before Italian defender Salvatore Bocchetti and forward Vladimir Dyadyun added one apiece after the break.