They still led by four points approaching the midway point of the second quarter at 29-25 but by half-time, the visitors had cut the gap to just one point.
When Ramos scored the first bucket of the half after the interval the visitors were back in front for the first time since the first quarter.
With three minutes left of the third, Lisboa E Benfica were still in front by a point - until they rattled off nine unanswered points to suddenly break the game open at 62-52.
Gregory Jenkins extended the lead to 12 points early in the fourth for the visitors but the home team rallied and came storming back to set up a nervy finale.
Down 69-57 they went on an offensive spree and came up with a rapid-fire 12-0 run to tie the game up with three minutes to play.
With just over 90 seconds to play the scores were still tied but a tip-in by Ramos and four free-throws sealed the deal for the Portuguese club.
Gregory Jenkins fired 20 points for the visitors while Ramos and Ben Reed both posted 15 points each.