The European Union and Russia kicked off a two-day summit on Monday overshadowed by disputes over Brussels lifting its arms embargo on the Syrian rebels and resolving to loosen Moscow's grip on EU natural gas supplies.
EU dignitaries said Russia's questionable human rights record would also come under the microscope at the talks in the industrial Ural Mountains city of Yekaterinburg.
Russian President Vladimir Putin will hope to build on his rapport with the visiting EU duo of President Herman Van Rompuy and Commission head Jose Manuel Barroso when he hosts a dinner late Monday ahead of a full day of talks on Tuesday.
Both analysts and officials said little progress was expected at the summit preceded by months of jousting over the Syria crisis and Russia's attempts to keep a stranglehold on European energy needs.
Talk of an all-encompassing treaty between the two sides has meanwhile been all but abandoned -- as has the hope of Russians getting their long sought visa-free travel to Europe this year.
The disputes only kept on mounting on Monday when Brussels expressed dismay over Moscow's surprise plan to slap new rules on the exchange of information collected by airlines during reservation and check-in procedures.
The European Commission said it still had no details about Moscow's new requirements less than a month before the measure was supposed to go into effect.
"Right now, our relations with Europe are the worst they have been in the entire post-Soviet history," said Maria Lipman of the Carnegie Moscow Centre.
Moscow and Brussels have had lukewarm ties ever since Putin rose to power in 2000 with a mission to raise Russia's influence and a determination to turn a blind eye to any criticism of his policies from the West.
Yet no other issue has been as divisive as the European Union's strong backing of the Syrian opposition and Putin's continued support for President Bashar al-Assad.
"The subject of Syria will be one of the priority areas at the talks," Moscow's EU envoy Vladimir Chizhov said ahead of the meeting.
Russia's Defence Minister Sergei Shoigu even went so far as to suggest that the move to arm Syrian rebels untied Moscow's hands to supply arms to Assad heretofore banned by international treaties.
Analysts believe Moscow and Brussels may try to smooth out their differences by issuing a statement of support for a proposed peace conference on the crisis that is meant to get Assad's camp and the main opposition group involved in direct talks for the first time.
But it is less clear how the two sides intend to resolve their growing differences over the powerful role enjoyed by Russian natural gas giant Gazprom in the European market.
Russia accounts for about a third of the 27-nation bloc's gas supplies -- a dominance that has allowed Gazprom to dictate prices for many years.
The dispute culminated in an EU decision in September to launch a probe into Gazprom's pricing strategy.
Putin's foreign policy adviser Yury Ushakov called the action against Gazprom "discriminatory".
Analysts said this row on its own was enough to scuttle the chances of Moscow and Brussels making any significant advances in Yekaterinburg.
"We can forget about seeing the signature of a framework Russia-EU agreement until they settle the issue of working around Europe's new natural gas rules," said Olga Potyomkina of the Russian Academy of Sciences' Institute of Europe.
But the tensions could soar even higher when EU leaders raise the issue of Russia's deteriorating rights record under Putin's 13-year rule.
EU foreign policy chief Catherine Ashton said Brussels was particularly concerned about a new crackdown on non-governmental organisations with foreign funding that are forced to wear a "foreign agent" tag.