The coming days could prove crucial in determining the outcome of the six-year Syrian war, as three separate summits put pressure on both the opposition and president Bashar Al Assad to end the conflict.
On Wednesday, the presidents of Turkey, which backs rebel groups, and Assad allies Iran and Russia will meet in the Russian city of Sochi to discuss reducing violence and boosting the delivery of aid.
On the same day, groups opposed to Mr Al Assad meet in the Saudi capital for three days for talks aimed at reinvigorating the weak and fractured opposition and forming a negotiations team to represent it at UN peace talks in Geneva the following Tuesday.
Few have hopes the Geneva peace talks will result in a breakthrough, however, with seven previous sessions between the Syrian regime and the opposition failing to overcome the main obstacle: the fate of Mr Al Assad.
Haid Haid, a consulting research fellow at the London based think tank, Chatham House, said: "The opposition, and some other international actors, view the Sochi summit as a Russian attempt to sideline the Geneva talks, which will only be beneficial for the regime," he said
Sochi summit
On Sunday, Turkish foreign minister Mevlut Cavusoglu met with his Russian and Iranian counterparts in the southern Turkish resort of Antalya to prepare for the Sochi summit.
Mr Lavrov called the meeting "very productive" and said the three men had agreed on "all the main issues".
The Sochi summit, hosted by Mr Putin, is considered to be a highly symbolic meeting of an emerging three-country geopolitical bloc — Russia, Iran and Turkey — that already has significant influence over Syria and the Middle East.
Top of the summit's agenda is reducing violence in Syria and ensuring that humanitarian aid are delivered to those in need.
'"According to previous leaks, the talks will likely be discussing a lighter version of the 2254 resolution, ie: local elections, new constitution but without a political transition," Mr Haid said.
UN Security Council resolution 2254 was adopted in December 2015 and outlines a road map for a peace process in Syria, while setting a timetable for talks between government and opposition members. It also sees an inclusive and Syrian-led political process that meets the aspirations of the Syrian people as the only sustainable solution to the current crisis in Syria.
Moscow, which has a military advantage in Syria, wants to focus on forming a solution with the other regional guarantors, Iran and Turkey, while avoiding the UN's peace efforts.
Mr Putin will be eager for the Sochi summit to succeed with a deal signed off ahead of the Russian new year in January and elections in March.
Mr Putin and Mr Erdogan have met five times already this year and spoken by telephone 13 times. They last met in Sochi on November 13, and agreed on the need to boost efforts for a lasting settlement in Syria.
Although Turkey has supported rebels looking to overthrow Mr Al Assad’s government, it has increasingly refrained from criticising the Syrian regime.
Riyadh meeting
Ahead of the Geneva talks, meanwhile, Riyadh will host the High Negotiations Committee — the main umbrella group representing Syrian opposition groups — along with other opposition figures.
The talks aim “to bring its [the opposition] parties and platforms closer together and unite its negotiating delegation to resume direct negotiations in Geneva under the auspices of the UN”, the official Saudi Press Agency said.
The High Negotiations Committee was formed in Saudi Arabia in 2015 to replace the Syrian National Coalition, which preceded it as the internationally-recognised representative of the Syrian opposition.
The talks come as the head of the umbrella group that represented the opposition at the previous rounds of talks, Riyah Hijab, stepped down on Monday.
Mr Hijab tweeted that he had been "forced to announce his resignation but wished the committee further achievements". He was a former Syrian prime minister under Mr Al Assad.
A number of other political opposition groups and figures backed by other countries including Russia and Egypt also exist and will be taking part in the talks.
Saudi Arabia, a leading backer of Syrian rebels, supports an international agreement on the future of Syria but maintains that Mr Al Assad should have no role in any transition to bring the war there to an end.
Astana talks
Moscow, Tehran and Ankara are sponsoring the Astana peace talks, named after the Kazakh capital where they are held. The talks have had some success in creating "de-escalation" zones in key areas of Syria.
The three countries brokered a ceasefire in Syria in December 2016, which led to the talks in Astana. The talks are being held in parallel to UN-backed discussions in Geneva to find a political solution to the conflict.
Earlier this month, Mr Putin and Donald Trump met on the sidelines of a regional summit in Vietnam and agreed that "only a political solution will do for Syria, rather than a military one".
While Russia has backed Syrian government forces in the war, the United States has backed rebel groups. The two leaders also called for elections in Syria, without specifying whether they should be presidential or parliamentary.
European leaders along with Mr Trump have all called for Mr Al Assad to step down since the beginning of the country's civil war.
