CSKA kept their Russian title chances alive by beating Spartak 2-0 in Moscow's most famous derby on Saturday to move third in the league, four points behind leaders Zenit St Petersburg.

Spartak started brightly but squandered several presentable chances and CSKA made them pay in the second half.

Teenage Iceland midfielder Arnor Sigurdsson scored twice within the space of nine minutes to give CSKA a crucial victory.

"Spartak started aggressively but we resisted their pressure," CSKA manager Viktor Gancharenko said. "It's a very important win."

Second-placed Krasnodar snatched a 1-0 win over Samara to narrow the gap on Zenit to three points as Viktor Claesson scored an injury-time penalty.

Krasnodar have won three straight games, but Zenit can restore their six-point lead on Sunday when they visit reigning champions Lokomotiv Moscow.

The hosts dominated possession, but a combination of poor finishing and good goalkeeping by Sergei Ryzhikov left the 23,000 home crowd frustrated at half-time.

They suffered a serious blow with 19 minutes to play as wing-back Sergei Petrov was sent off.

The game looked to be heading towards a goalless conclusion, but Krasnodar defender Uros Spajic was brought down in the area and Sweden international Claesson netted a 'Panenka' spot kick.

"We failed to show our best football today and Petrov's red card also complicated the situation for us a great deal, but nevertheless we managed to win," Krasnodar head coach Murad Musaev said.