Russian Premier League leaders CSKA Moscow will undergo a stern test of their title ambitions on Sunday when they visit reigning champions Zenit St Petersburg.

The match represents a key game in an increasingly exciting title race, that has seen several sides keep themselves in contention with just nine matches to play.

CSKA's lead is far from unshakeable as they are just two points ahead of second-placed Rostov, while Lokomotiv Moscow are three points further back in third, with Zenit fourth, six points behind CSKA.

CSKA and Russia head coach Leonid Slutsky, who oversaw the national side's 4-2 friendly defeat to France on Tuesday, said his players will need to switch their focus back to domestic games after fulfilling their international commitments.

"The match in Paris gave me a lot of food for thought but it's history now," Slutsky said. "Now we need to revert back immediately to our remaining commitment this season, the national championship, as we want to maintain our lead.

"I expect a very hard clash in Saint Petersburg. There's no doubt that Zenit intend to defend their title and the upcoming match is an excellent chance to improve their position in the table."

Zenit manager Andre Villas-Boas meanwhile expressed confidence that his team were on course to retain their title, especially if they could grab a win on Sunday.

"We're now six points from CSKA. That is not that much," the former Porto, Chelsea and Tottenham Hotspur coach said.

"We can narrow the gap to just three points if we win the next game. But a single win is not enough and we need to keep on winning.

"I believe we can become the champions again, though a lot of teams are still in the race for the first place. Possibly everything will be decided in the very end of the championship."

Meanwhile, Rostov need a win in their home match with Spartak Moscow on Saturday to give a boost to their unlikely title challenge and, temporarily at least, move top of the table.

"I want my team to produce a breakthrough this season," manager Kurban Berdyev, who led Rubin Kazan to their back-to-back titles in 2008-09, told Rostov's official website.

"I'm confident that it's feasible. But we all need to show our best in the remaining matches to make it happen."

However, nine-time champions Spartak, who have been ordered by owner Leonid Fedun to qualify for European football, will need to take all three points to keep their chances of a top-four finish alive.

"There are nine matches ahead and every one will be the deciding one for us," Spartak head coach Dmitry Alenichev said. "We have no right to make errors any more.

"Rostov are very well-organised team and they're on the rise. But they also have weaknesses. We will just need to capitalise on their mistakes," he added.

Fixtures (all times GMT)