Zoo bosses are "confident" about the pregnancy prospects for the UK's only female giant panda, amid expectations that she will be ready to mate within a fortnight.
Experts at Edinburgh Zoo have been monitoring Tian Tian's hormones and believe she will soon enter her brief fertile period.
They hope she and resident male panda Yang Guang will produce a cub this year as the animals both start to show the tell-tale signs that they are ready to breed.
But experts cautioned that there are no guarantees the pair will soon hear the patter of tiny paws.
Latest hopes of Tian Tian falling pregnant follow last year's disappointment when the pair did not mate. Although she was artificially inseminated, she lost her foetus at late term.
Tests have shown the panda's oestrogen levels rose higher than her progesterone levels earlier this week - a key sign that she will be ready to breed in the next seven to 14 days.
Speaking at the zoo today, Iain Valentine, director of the giant panda programme at zoo operator the Royal Zoological Society of Scotland (RZSS), said: "Tian Tian has had the crossover in her hormones, so that means we're now into the 14-day point where she will actually hit peak. We don't know exactly when that's going to be.
"What we're doing now is bringing all the expertise together to help us work our way through the whole process.
"Yang Guang is really getting bigger and bigger. He's filling himself up with bamboo, trying to put on lots of weight and energy for breeding.
"This year there's been a lot more recognition and scent marking going on between the two and that's been happening for quite some time now. As we're getting closer and closer to breeding it's becoming more intensive.
"Over the next few days we'll put the male into the female enclosure and vice-versa, so they're picking up the chemical cues from each other."
Mr Valentine has described panda breeding season as a "delicate and complex" affair.
Experts are now watching Tian Tian's behaviour closely to gauge when her 36-hour breeding window begins.
Professor Wang Chengdong, from the China Conservation and Research Centre for Giant Pandas (CCRCGP), was due to arrive in Edinburgh today to help decode both pandas' behaviour in the run-up to the mating period.
If the pandas do not mate then artificial insemination will take place. This would be overseen by specialists from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin.
Mr Valentine said: "We know that we got her pregnant last year and hopefully it will be all the way through to a cub in August or September.
"We're positive, we remain positive. We know that we have a pair of pandas which have bred before, although obviously not with one another. Tian Tian is a proven mother so we have all the right ingredients."
RZSS chief executive Chris West said the two animals seem calmer and more settled this year.
He said natural mating is preferable , but that artificial insemination would take place if that did not occur.
"Last year she was pregnant so we are confident that we can get her pregnant but there is no guarantee - this is nature, it's biology," he said.
"But we are confident and we have a great team here."
On a possible future cub birth at the zoo, he said: "Pandas are truly endangered so any new cub is important.
"And when people come here, and more and more people will come here to see a cub, they are connecting with conservation in some way."