Russian President Vladimir Putin will host EU chiefs for an informal dinner on Sunday at the start of a two-day summit overshadowed by clashing visions on Syria and Iran.
EU Commission chief Jose Manuel Barroso and EU President Herman Van Rompuy will be keen to sound out Putin for any hints of a softening on either crisis after his return to the Kremlin for a third term.
But the ex-KGB agent stuck firmly to his refusal to back further action against Soviet-era ally Syria during a swing through Berlin and Paris on Friday, and there were few hints of compromise emerging from Moscow.
"We intend to once again underscore our principled approach to settling international conflicts," Putin's foreign policy adviser Yury Ushakov told reporters ahead of the 29th Russia-EU talks.
Pressure on Russia to concede that no peace talks are emerging and to promote a Syrian compromise in which President Bashar al-Assad would cede power, if only to his inner circle, has been building on an almost daily basis.
A US official said Secretary of State Hillary Clinton told her Russian counterpart Sergei Lavrov by telephone Saturday that "we've got to start working together to help the Syrians with Syria's political transition strategy."
The European Union plans to deliver a similar message to Putin in his native city of Saint Petersburg during Monday's more formal set of meetings.
We "expect to have an in-depth discussion over Syria," said an EU official in Brussels.
"We must act together with Russia. Russia needs to assume its role and influence. A way out of the current situation needs to include Russia," the EU official said.
Putin has conceded that Syria stands on the brink of civil war despite Russia's adamant support for mediator Kofi Annan's tattered plan for ending a 15-month conflict in which 13,000 are thought to have died.
But Putin has cited the examples of Libya and Iraq -- two foreign interventions Moscow also bitterly argued against -- as evidence that transitions of power and outside interference do not solve problems in the long term.
Russia's dispute with the West over Iran also concerns what Moscow sees as attempts by Western nations to circumvent its diplomatic sway on the UN Security Council by acting on their own.
The Kremlin has criticised the European Union sharply for imposing an oil embargo on Iran over its nuclear programme and argued that unilateral sanctions only diminish the chances of compromise from Tehran.
Van Rompuy countered in an interview with Moscow's Kommersant business daily that "whether we maintain, lift or ease sanctions (against Iran) will depend on its own future actions."
Yet the two sides could still seek out common ground ahead of a crunch third round of talks with Iranian negotiators that world powers have scheduled to hold in Moscow on June 18 and 19.
Moscow has been keen to stress that its ties with the European Union itself -- a 27-nation bloc representing Russia's top foreign trade partner -- remained warm and were seen as vital by Putin.
"Overall, we believe that enhanced strategic partnership between Russia and the EU is not only useful, it is essential to all sides," Russia's EU envoy Vladimir Chizhov said in Brussels.
Some analysts cautioned however that EU officials who hope so see a more accommodating Putin on his return from a four-year spell as Russian premier may be disappointed.
"Based on his recent rhetoric and statements, he has not become any more cooperative than he was (during his 2000-2008 presidency)," said Institute of Strategic Assessment analyst Alexander Konovalov.
"If anything, should the financial crisis worsen, he might defend the nation's interests more adamantly still."