It was the most anticipated event of the year, at least in the panda enclosure at Edinburgh Zoo: would Yang Guang and Tian Tian become more than just companions?
The male and female pandas were closely watched for 36 hours in the hope they might take the first steps towards parenthood - only for disappointment to ensue.
Tian Tian, it seemed, was the key, as she is only able to reproduce once a year, for a day and a half.
But now research has suggested that it may in fact be a case of "it's not you, its me" for Yang Guang.
The bad news for male pandas comes from research which shows they have only 24 days a year at their reproductive peak.
While much longer than the female breeding period, in the wild these are timed to coincide - but in captivity this can become mistimed and the chance of successful mating becomes low, according to the scientists behind the work.
Dr Copper Aitken-Palmer, veterinary medical officer at the Smithsonian Conservation Biology Institute in Virginia, said: "The reproductive strategy the giant panda works well for them in the wild, otherwise, they would not have evolved to develop this strategy.
"However, once we brought them into captivity, we changed all the rules. Frankly, we as scientists and animal managers were the ones that did not fully understand the complexities involved in giant panda reproduction."
Dr Aitken-Palmer spent three years working with scientists at the Chengdu Research Base of Giant Panda Breeding in China to study the reproductive cycle of male pandas.
While it is now well known that female pandas only enter oestrus, or "heat", for 24 to 72 hours between February and May each year, the new work has revealed that for much of the year male pandas are not interested in sex either.
During the winter, however, their bodies flood with hormones that gradually ready them for mating, according to the research, which is published in the journal Biology of Reproduction.
The biologists found that the animals reached their reproductive peak between 22 March and 15 April, when their bodies are producing the most sperm. By June their interest in mating had disappeared again.
Keepers at Edinburgh Zoo last week had hoped that Yang Guang and Tian Tian, who are on loan from China for 10 years, might mate and produce the first panda cub to be born in the UK.
The pair wrestled, grunted and sniffed. But after two days of trying, with Yang Guang even mounting his female counterpart several times, hopes of successful mating ended in anti-climax.
The zoo will let the animals try again next year but will try to build up the anticipation between them by switching them between enclosures to mimic the way in which a male panda will seek out females in the wild for breeding.
Iain Valentine, director of research and conservation at Edinburgh Zoo said: “Each time the pair met we saw a huge amount of eagerness and attraction between Tian Tian and Yang Guang.
“There was lots of vocalisation and encouragement from our female and physical contact between the two. He mounted her several times, however full mating did not occur.
“We are hugely encouraged by how much the natural sparks flew between the two animals, as like humans, not all male and female pandas are attracted to each other. Both were keen to mate, but their inexperience showed.
“Baby cubs would have been a bonus this year, but we have to appreciate that the pandas have only just arrived and have had limited time to settle.”