Hannah, 28, and partner Saskia Clark, who are competing in the women's 470 sailing, hold a 20-point lead going into the finale, after finishing second and third in yesterday's races.
This means they'll claim gold if they finish the race, which is due to get underway at 5.05pm (BST) today.
The pair have dominated throughout the event, winning three races and finishing in the top eight in all 10.
They missed out on gold at London 2012, taking silver as New Zealand edged them out in the medal race.
Hannah, who completed a diploma in Mechanical Engineering, is one of eight University of Bristol graduates at the Olympic Games.
Her medal will add to the silver won by fellow University of Bristol alumnus Tom Mitchell, who captained the men's Rugby 7s team to the final in Rio where they lost to Fiji.
Other medal contenders include Georgie Twigg, who scored a goal to help the Team GB women's hockey team reach the semi-finals. They play New Zealand at 9pm (BST) tonight and have high hopes of reaching the Olympic final on Friday, where the victor will play the winner of Germany vs the Netherlands.
Recent graduate Jazmin Sawyers is through to the final of the long-jump, which takes place at 1.15am (BST) tomorrow morning. The 22-year-old, who has just completed her Law degree, jumped 6.53m to qualify in 12th place.