European diplomats called the meeting at a lavish estate on the outskirts of Putin's hometown of St. Petersburg a chance to get reacquainted with the Russian leader, in power for 12 years and now formally in charge of foreign policy again.
But the crisis in Syria, where Moscow has blunted Western efforts to condemn President Bashar al-Assad and push him from power, may overshadow talks on trade and other issues at the twice-yearly summit.
Both Russia and Europe still have hope in Kofi Annan's UN-backed peace plan to end 15 months of bloodshed that Western nations blame on Assad.
But EU nations wish Russia would press the Syrian leader to withdraw weaponry and halt attacks as demanded by the plan, and want him to step aside to make way for a political transition.
"We need to make sure that Russia is using fully its leverage in convincing the regime to implement (the plan)," said an EU official, declining to be named.
"The Russian side has certainly not been very helpful in finding solutions in terms of a political way out."
Russia says it is not protecting Assad, who has given Moscow its firmest Middle East foothold, but that the Syrian leader's exit cannot be a precondition for political dialogue.
Putin ceded no ground in remarks during visits to Berlin and Paris on Friday, placing an accent on rebel violence, criticizing sanctions and saying political decisions could not be forced on Syria from outside.
EU foreign policy chief Catherine Ashton, who met Russian Foreign Minister Sergei Lavrov on Sunday, said in a statement: "Russia's role is crucial for the success of Annan's plan."
The EU wanted to "work closely with Russia to find a way to end the violence and support" the plan, said Ashton. The statement said she spoke to Annan by phone on Sunday and that they agreed the crisis had reached a "critical point".
Lavrov set a constructive tone in his own phone call with Annan, saying that to support the plan Moscow "will be ready to consider various scenarios of further work" that would help to coordinate international efforts on Syria, his ministry said.
However, when asked whether he expected the summit to narrow the gap on Syria, Lavrov told reporters: "I don't think so."
Same vision?
European Council President Herman Van Rompuy, European Commission President José Manuel Barroso and Ashton will try to gauge Putin's attitude towards the EU as he enters a new term as president for the next six years.
"This is about checking whether we have the same vision - where we want to go with our strategic partnership," the EU official said of the talks, held at the Constantine Palace, a renovated Imperial-era estate on the Baltic Sea.
Russia and the EU are deeply intertwined, with Europe relying heavily on Russian energy exports and Russia buying EU products from German cars to Greek olive oil and IKEA furniture for a growing middle class.
But they wrangle over issues ranging from energy supplies, trade and market access to human rights, hampering efforts to forge a new pact to govern their ties after four years of talks.
On Thursday, Russia's EU envoy Vladimir Chizhov reiterated criticism of EU regulations designed to liberalise its gas market by barring suppliers including Russian giant Gazprom from controlling transit pipelines.
Chizhov also said Russia wanted faster progress towards visa-free travel - a goal Putin, keen to shed an image as unwelcome neighbor, has long pursued.
The criticism over market access cuts both ways.
Russia is to join the World Trade Organisation this year, binding it to global rules, but the EU wants the Kremlin to lower barriers for Western companies and investment by curbing corruption and improving the rule of law.
Some EU officials are concerned Putin's return to the presidency will mean more state interference in the economy and slower reforms.
Putin, who has faced the biggest opposition protests of his rule, has warned against Western meddling.
He says integration among former Soviet republics will be a priority and made Belarus the first foreign destination of his new term, backing an authoritarian leader under EU sanctions. He leaves for Uzbekistan shortly after the summit.
