Chiefs aim to welcome up to 20,000 supporters to Twickenham for England's match against the Barbarians next month while Arsenal hope to welcome back fans.
Pilot events are taking place in several sports in England with a view to reopening doors to a limited degree from October 1.
On Saturday, 2,500 fans watched Brighton's friendly against Chelsea at the Amex Stadium -- the first time spectators have been allowed inside a Premier League stadium since the coronavirus lockdown in March.
Tickets for the Barbarians match on October 25 went on sale on Wednesday.
Eddie Jones' men are scheduled to travel to Rome to take on Italy in the postponed Six Nations contest a week later.
"We continue to work closely with government and the local authority on the return of sports fans to the stadium," said Rugby Football Union (RFU) chief executive Bill Sweeney.
"The numbers of fans able to attend, given social-distancing requirements, will be significantly lower than normal and subject to final agreement from government."
He said a test event would be held to test operational plans and demonstrate Twickenham was well-prepared.
The RFU said it had robust plans in place.
"The number of fans allowed into Twickenham Stadium for the fixture is based on social-distancing requirements to mitigate against the risk of Covid-19 transmission," the RFU said in a statement.
"Subject to obtaining the relevant licence and approvals including those from public health authorities, spectator numbers will be up to 20,000 -- less than 25 percent of the stadium's total 82,000 capacity."
Arsenal said on Wednesday they hoped to have fans back on a reduced-capacity basis for their home match against Sheffield United on October 3.
"In recent months we have been working very hard with the relevant authorities on plans to bring fans back to stadiums, and specifically Emirates Stadium, initially with reduced capacities," the club said in a statement on their website.
"Although our home fixture against West Ham United on Sunday 20 September will be played behind closed doors, based on the current UK government guidelines, we hope to be able to welcome supporters back to Emirates Stadium on a reduced-capacity basis from the Sheffield United game scheduled for Saturday 3 October."