Chinese Prime Minister Li Keqiang on Sunday arrived in Moscow for talks with President Vladimir Putin as Russia is struggling with its most pronounced isolation since the end of the Cold War.
"It is a major event in the bilateral relations," Chinese Vice Minister Cheng Guoping said ahead of Li's visit.
He said both sides would sign a joint communique and about 50 agreements. "We are confident it will be a success," he said.
Deputy foreign minister Igor Morgulov in Moscow said the two countries would sign a host of deals including on nuclear energy, natural gas, financing and banking.
"I am convinced that the Chinese Prime Minister's visit will allow us to make substantial progress in key areas of practical cooperation," he said in comments released by the foreign ministry on Sunday.
Li's first visit to Russia as premier comes at a sensitive time as the Kremlin is grappling with the consequences of its support for separatists in Ukraine during a six-month conflict in the east of the ex-Soviet country.
Besides meeting Putin on Tuesday, Li will also meet with his Russian counterpart Dmitry Medvedev and attend a forum on innovations during the three-day visit.
Li's Russia's trip is part of a week-long visit to Europe.
-'China against sanctions'-
Ahead of his Moscow visit, Li travelled to Germany for talks with Chancellor Angela Merkel. He will also participate in a summit in Milan next week.
Merkel, a fluent Russian speaker, has been seen as one of the European Union's top negotiators on the Ukraine crisis.
She has held regular talks with Putin but has also thrown her weight behind EU sanctions against Russia in a bid to make Putin drop support for separatists in eastern Ukraine.
Saddled with several rounds of Western sanctions and the Russian economy in tatters, the Kremlin appears keen to see an easing of punitive measures from the West.
Putin late Saturday ordered a pullback of troops from the border with Ukraine and will hold key talks with Ukrainian President Petro Poroshenko on the sidelines of an Asia-Europe meeting in Milan next week.
China has spoken out against Western sanctions against Russia.
"China always opposes the wilful use of sanctions or the threat of sanctions," said Cheng.
"We welcome the moves by various parties to encourage the momentum of a political settlement of the Ukrainian issue."
Once bitter foes during the Cold War, Moscow and Beijing have over the past years ramped up cooperation as both are driven by a desire to counterbalance US global dominance.
China and Russia often work in lockstep at the UN Security Council, using their veto power as permanent council members to counter the West on issues such as the Syria crisis.
Russia's showdown with the West over Ukraine has given Kremlin a new impetus to court Beijing.
Resource-hungry China is seeking to diversify its sources of energy amid booming domestic consumption, while Russia is seeking to tap fast-developing Asian markets.
After a decade of tough negotiations China and Russia inked a 30-year, $400-billion agreement in May that will eventually involve 38 billion cubic metres of gas annually.
Critics however disparaged the terms of the deal, saying Putin, in his bid to spite the West, signed an agreement that was more beneficial to China than Russia.