MOSCOW -- Secretary of State John Kerry had just made an offhand remark about how President Bashar al-Assad of Syria could avoid a military strike -- and now Sergey V. Lavrov, Russia's hard-charging foreign minister, was on the phone.
Mr. Lavrov was not about to let the moment pass.
What aides to Mr. Kerry were already trying to roll back, Mr. Lavrov seized on, telling Mr. Kerry he would immediately go public with a Russian-led proposal to dismantle the Syrian chemical weapons arsenal. That prompted a sharp response from Mr. Kerry who warned in the 14-minute call, "We are not going to play games."
By the time Mr. Kerry's plane landed back in Washington, the ground had shifted and on Saturday, not a week later, Mr. Kerry and Mr. Lavrov completed the plan sitting by the pool at a Geneva hotel.
It is a pact that American arms control experts have scrambled to shape and that the White House believes may be the best way to the uphold prohibitions against the use of poison gas without resorting to military force. But it is also one that the Kremlin clearly thinks serves the interests of Russia and the Syrian government.
In many ways, Mr. Lavrov's work over the next six days represented the apex of a career largely spent trying to body-block what the Kremlin has long viewed as dangerous American unilateralism. It is a job he has done so effectively that it has earned him the nickname "Minister Nyet," and senior American officials, including Hillary Rodham Clinton and Condoleezza Rice, have said they often found it infuriating to deal with him.
As the diplomatic technician for his boss, President Vladimir V. Putin, Mr. Lavrov maneuvered to hem in the United States, averting a unilateral military strike and reasserting Russia's role -- all while Russia was continuing to provide weapons to Mr. Assad and diplomatic cover for his effort to suppress an uprising.
More broadly, though, Mr. Lavrov has sought to force the United States into a conversation that the Kremlin hopes will set a precedent, establishing Russia's role in world affairs based not on the dated cold war paradigm but rather on its own outlook, which favors state sovereignty and status quo stability over the spread of Western-style democracy.
In doing so, Mr. Lavrov relied on his long experience, not just on nearly 10 years as foreign minister. He served more than a decade as Russia's ambassador to the United Nations, where he developed an intricate knowledge of the workings of the Security Council, as well as deep experience in international disarmament efforts, including in Iraq.
"For now, he's one of the most skilled diplomats in the world," said Fyodor Lukyanov, editor in chief of the policy journal Russia in Global Affairs. "The time of real diplomacy has come back."
For Mr. Lavrov it is a series of events he has long prepared for. He graduated from the Moscow State Institute of International Relations in 1972 and moved to New York in 1981 to work at the United Nations after brief stints in Sri Lanka, and in Moscow.
At the United Nations, he was known for his elaborate, seemingly absent-minded doodling during lengthy meetings but also for a command of the issues.
"He was a great doodler, but his mind was always spinning away," said Charles A. Duelfer, who was deputy head of the United Nations' weapons inspectors program in Iraq in the 1990s and frequently met with Mr. Lavrov at the United Nations headquarters in New York.
Mr. Duelfer said that Mr. Lavrov's long experience with United Nations inspectors working to remove unconventional arms from Iraq helped him to quickly assess the situation in Syria and to work out a detailed plan with Mr. Kerry. "He knows this stuff because he lived through it in Iraq," Mr. Duelfer said. "He's knows what's possible when you have independent inspectors."
A more cynical view, analysts and Western diplomats said, is that Mr. Lavrov was after a political objective, not one of disarmament, using diplomatic jujitsu to buy time for the Assad regime.
A senior State Department official said the American side was surprised at a lack of specificity in an opening statement by Mr. Lavrov in Geneva, which prompted American experts to insert detailed provisions and deadlines to try to turn it into a workable plan. Mr. Lavrov, a chain-smoker, is known as an old-school diplomat. He flatly ignored an effort by Secretary General Kofi Annan to ban smoking in the United Nations headquarters, saying Mr. Annan did not own the building. He enjoys whiskey and cigars, and his hobbies tend toward action sports like rafting and skiing.
He can show flashes of anger. When a photographer asked Mr. Lavrov, Mr. Kerry and the special envoy, Lakhdar Brahimi, to pose after a meeting in Geneva, Mr. Lavrov said: "You don't give us orders; you just capture the moment."
Mr. Lavrov, 63, and Mr. Kerry, 69, seem to have formed a quick bond, with late-night dinners, fireside drinks and garden strolls. To some, especially in the West, Mr. Lavrov's machismo and old-fashioned chivalry sometimes seem to border on sexism. Admirers say it is just gentlemanly charm.
The former Austrian foreign minister, Ursula Plassnik, called Mr. Lavrov "one of the most knowledgeable and respected foreign policy actors in the global village." On her first visit to Moscow, she said, Mr. Lavrov was waiting for her outside the legendary Café Pushkin with a bunch of yellow roses.
"In backstage discussions, I occasionally had to remind Sergey Lavrov not to try to 'bulldoze' me or others, which he usually accepted with a smile," she said. "I was not the least surprised to see him move center stage with ease and determination in the Syrian crisis management."
That Mr. Lavrov was enjoying the moment in Geneva was clear to the Russian reporters who cover him. Still, he was not happy as much as satisfied, they said. Approached with a question early Saturday outside the hotel, Mr. Lavrov told a Spanish-language television reporter that she was "beautiful." Before the news conference, he joked with reporters, apologizing for the wait.
A reporter tried to get ahead of the announcement asking, "Have you got an agreement?" Mr. Lavrov quipped, "So bloodthirsty." When another asked if he had spoken to the Syrian government, he said, "No, have you?"
He bantered in perfect English, though when asked to answer a question in English during the news conference later, he refused, insisting on Russian during the formal proceedings.
Georgi I. Mirsky, a political scientist at the Institute of World Economy and International Relations, said that the Syria plan was really Mr. Putin's but that Mr. Lavrov will get the credit.
"In history textbooks, it will be Lavrov and Kerry -- Lavrov the great man, he saves Syria from American military strikes, and also saves Barack Obama from a humiliating and embarrassing situation in the Congress," Mr. Mirsky said. "He is a bureaucrat, he is a good diplomat. He knows the score. And he will never ever say anything that will contradict the official line."
Mr. Mirsky added: "Of course, there is a certain dose of risk here, because Bashar Assad may spoil the whole picture. If he decides to use chemical weapons again, it will be very nasty."
David M. Herszenhorn reported from Moscow, and Michael R. Gordon from Geneva. William J. Broad contributed reporting from New York, and Steven Lee Myers from Valdai, Russia.
Correction: September 17, 2013, Tuesday
This article has been revised to reflect the following correction: An earlier version of this article misidentified the site at a Geneva hotel where Secretary of State John Kerry and Russian Foreign Minister Sergey V. Lavrov finalized the plan to dismantle Syria's chemical weapons. It was by the pool, not at a cafe table.world
This article originally appeared in The New York Times.