* Zenit rout Rostov to go top
* Spartak thump CSKA in Moscow derby (Writes through with Zenit win)
MOSCOW, Sept 22 (Reuters) - Zenit St. Petersburg nosed ahead of Spartak Moscow at the top of Russia's first division on Sunday after both teams celebrated emphatic wins and leapfrogged champions CSKA on superior goal-difference.
Spartak first dislodged bitter city foes CSKA after drubbing them 3-0 in the lunchtime Moscow derby before Zenit edged into the driving seat with a 4-0 win at sixth-placed Rostov, leaving the three front-runners locked on 20 points, one ahead of fourth-placed Lokomotiv Moscow.
Hulk was in blistering form as he scored one goal and set up two for Zenit, who took a 51st minute lead after the Brazil striker fed Portuguese forward Dani to dink his shot over Croatia keeper Stipe Pletikosa.
Former Arsenal striker Andrei Arshavin doubled the lead with a slick finish before Hulk got on the end of a teasing cross by Argentine left back Cristian Ansaldi and turned it in from close range.
Midfielder Viktor Faizulin walked the ball into an empty net in the closing stages after a quick one-two by Arshavin and Dani left the bedazzled Rostov defence flat-footed.
Spartak brushed aside CSKA 3-0 and completed a difficult week for their cross-town rivals after they suffered a 3-0 Champions League defeat by holders Bayern Munich in their Group D match on Tuesday.
The result in no way flattered Spartak, who could have scored a hatful of goals and were denied a bigger win by a string of superb saves from CSKA goalkeeper Igor Akinfeev.
Russia's first-choice keeper kept his team afloat for as long as he could but was powerless in the 40th minute, when Aras Ozbiliz volleyed home a perfect cross from the left by Argentine defender Tino Costa.
The floodgates opened shortly after the break after Akinfeev had palmed over a header by Yura Movsisyan, who could have had a hat-trick as his link-up play with fellow Armenian Ozbiliz left their markers chasing shadows throughout.
Kirill Kombarov made it 2-0 in the 52nd minute after Brazilian Joao Carlos flicked on a corner at the near post for the midfielder to head the ball into the empty net from five metres, sparking wild celebrations among Spartak fans.
The home faithful had even more to cheer about seven minutes later when Kombarov beat his marker and floated a delightful cross for captain Sergey Parshivlyuk to head coolly into the far corner past Akinfeev. (Writing by Zoran Milosavljevic in Belgrade; Editing by Justin Palmer/Rex Gowar)