Saudi Arabia had hoped for an in-person Riyadh summit, but in September announced it would be held virtually because of the coronavirus.
On Friday, Turkish President Recep Tayyip Erdogan and King Salman of Saudi Arabia spoke by telephone, according to statements from both leaders.
In his opening remarks, Saudi Arabia's King Salman spoke to a screen of global leaders, including Trump, and highlighted the economic support G-20 members had contributed to combating the coronavirus pandemic and economic fallout. He will also encourage other leaders to step up and support the Covax initiative, to ensure developing countries are not frozen out of the race for a vaccine. The pandemic has offered the G-20 an opportunity to prove how such bodies can facilitate worldwide cooperation in crises - but has also underscored their shortcomings.
Guterres called on more G-20 nations to join COVAX, an global initiative to distribute COVID-19 vaccines to countries worldwide.
Speaking at the G20 Summit, Prime Minister Narendra Modi Saturday said there was a need to develop a new global index "based on talent, technology, transparency and trusteeship towards the planet".
Outgoing US President Donald Trump had aligned himself closely with Saudi Arabia, hailing its purchases of US weapons and hostility toward US adversary Iran. The World Health Organization says more cases of COVID-19 have been reported in the past four weeks than in the first six months of the pandemic.
The gathering also comes at a time of deep political tension within the United States, with a doubt over whether or not Trump will address the attendees.
As part of the summit, seven leaders released video messages on "Pandemic Preparedness and Response".
Her words were echoed by French President Emmanuel Macron, who also adressed leaders. German Chancellor Angela Merkel called for strengthening the World Health Organization and stressed the pandemic can only be overcome if an affordable vaccine is available to all nations.
"We must also continue to support the global economy and reopen our economies and borders to facilitate the mobility of trade and people", King Salman said.
After his moment in the virtual limelight, Trump was substituted by Treasury Secretary Steven Mnuchin as the other world leaders had their say.
Leaders of the world's 20 biggest economies on Sunday will pledge to pay for a fair distribution of COVID-19 vaccines, drugs and tests around the world so that poorer countries are not left out, and to extend debt relief to them, a draft G20 communique showed. At the time, they vowed "to do whatever it takes to overcome the pandemic".
"I am confident that the Riyadh summit will deliver significant and decisive results and will lead to adopting economic and social policies that will restore hope and reassurance to the people of the world, " King Salman said.
The G20 launched the DSSI in April to address the immediate liquidity needs of low-income countries, allowing the debt service payments due from May 1 to the end of the year owed by the most impoverished countries to be suspended.