Shortened to less than three hours after a dinner on Monday was dropped, President Vladimir Putin will be hosted by European Council president Herman Van Rompuy and European Commission head Jose Manuel Barroso.
They meet against the backdrop of sharpening differences over relations with Eastern Europe, highlighted by the Ukraine impasse, together with trade frictions, plus a series of international issues such as Iran and Syria where Moscow and Brussels do not see eye to eye.
Brussels rejects suggestions that the shortened summit format reflects unhappiness with Moscow but readily concedes it "is not a summit like the others."
"We have decided to have a shared reflection between the leaders on the direction and nature of our partnership," European Commission spokesman Olivier Bailly said Friday.
Accordingly, Van Rompuy, Barroso and EU foreign affairs head Catherine Ashton will meet Putin plus Foreign Minister Sergei Lavrov alone with a minimum of aides, Bailly said, "so as to have a frank and transparent exchange."
"Our relations are in a challenging period and these exchanges will allow us to look, to see how we can move forward," he added.
Ukraine dominates after President Viktor Yanukovych in November unexpectedly ditched an association agreement with the EU, under pressure from its Soviet-era master, sparking violent and continuing protests.
"Europeans were never prepared for ... Putin plunging them into a vicious zero-sum game over ... Central and Eastern Europe," said Bruno Lete of the German Marshall Fund.
Angered, Brussels seems at a loss how to respond while Putin presses ahead with his Eurasian Customs Union project to bring former Soviet states back into Moscow's fold.
"As a result, Europe's eastern neighbourhood is not transforming into a region of liberal, well-governed countries but into a collection of economically weak nation states ruled by semi-authoritarian regimes loyal to Moscow," Lete said.
Moscow resents 'interference,' chides EU
Russian Ambassador to the EU Vladimir Chizhov has been active in recent weeks in Brussels, rejecting such ideas as missing the true nature of the relationship.
Russia and its customs union "is neither an EU geopolitical rival nor a Soviet Union Mark 2.0," Chizhov told a recent seminar on the summit.
Rather, its policies simply amount to a "restoration of traditional ties in the region," and the two sides should be able to meet on that basis.
Asked about the Russian loan of $15 billion to Yanukoych just after he dropped the EU pact, Chizhov laughed and said: "Nobody prevented an EU financial contribution!"
All is not lost, however hard the going may be.
The situation may be difficult but "Putin is a very strong (and) ... also utterly pragmatic," which means the two sides can do business, one EU diplomat said.
Business means trade worth nearly 340 billion euros in 2012, with the EU running a large deficit of 91.6 billion euros as it remains heavily reliant on Russian energy, a fact of life that binds the two together.
"There is no question but that for a very long time the EU-Russia energy relationship will remain very strong," said Michal Baranowski, director of the German Marshall Fund office in Warsaw.
Baranowski said that while the summit could prove "very frank," the diplomatic term for very difficult, he did not see a breakdown in ties.
"A breakdown is not good for the EU, is not good for Russia ... people will be pragmatic given the wider interests at stake -- economic, energy, international issues," he said.
Putin may not think very much of the current EU leadership, which will be replaced later this year, but he will bide his time, Baranowksi said.
"There is a lack of respect as Russia sees this team as very weak ... but the next summit (with the new leadership) is the important one," he said.