Rubin, who set up two of Siena's three goals, has urged his teammates to ignore the table for now and just keep picking up wins.
"Do we believe that we can survive? Sure," Gazzetta dello Sport quotes Rubin as saying.
"We never gave up hope. We knew that Lazio would be a tough game and we are delighted with the win. We must not look at the table and just continue to play well."
The result moved Siena off the bottom to 18th and they are now four points away from Genoa in 17th.