The only pandas in the UK have now been brought together as the female has been judged ready to mate.
Keepers opened a so-called love tunnel between male Yang Guang and female Tian Tian's enclosures today after tests showed she had ovulated.
Female pandas ovulate just once a year, giving a window of 36 hours in which they can get pregnant.
The bears were introduced this morning and will also be brought together later in the day.
Edinburgh Zoo has turned off the "pandacam" which allows people to watch the animals online.
A zoo spokesman said: "The love tunnel is being opened and the bears will be able to meet each other that way. Today is the first time they have been introduced to each other."
Giant pandas Tian Tian (meaning Sweetie in English) and Yang Guang (Sunshine) arrived in Scotland from Ya'an reserve in Chengdu, China, on December 4 last year. They went on show to visitors for the first time on December 16.
Earlier this month the zoo said it might stream any birth live on the internet.
The panda enclosure has a camera already installed, allowing people to watch the animals every day.
Speaking last week, Iain Valentine, director of research and conservation at the zoo, said: "We are hopeful of a positive outcome. However, we are realistic that this is only the very first year that Tian Tian and Yang Guang have been in Scotland and that we also have 10 more to go.
"If Tian Tian does get pregnant, confirmation of this may also not be straightforward. Female pandas often have pseudo-pregnancies where their behaviour and hormones indicate they are pregnant for fairly long periods of time when in fact they're not.
"Also, experts do not know how long panda gestation periods actually are, as female pandas practise delayed implantation. Panda pregnancies can be anything from 85 to 100 days."Tian Tian and Yang Guang are the first giant pandas to live in the UK for 17 years.