The pandas at Edinburgh Zoo could mate within days, say experts from the Royal Zoological Society of Scotland.
Tian TIan, the female panda, will shortly be in heat, hormone tests have revealed, and the crucial 36-hour "mating window" is likely to arrive within days, said RZSS experts.
The female panda had previously been "grumpy" and "off her food" this week - and hormone tests have now confirmed that the brief window where she is able to conceive is approaching.
Tian Tian's urine is tested twice daily to help staff pinpoint the "mating window". When it arrives, the pandas will meet to have the opportunity to mate.
The male panda, Yang Guang, has been played tracks on Smooth Radio to get him in the mood, and trained to walk through the "love tunnel" that connects the two pandas' enclosures.
Tian Tian and Yang Guang have lived at Edinburgh Zoo since December 2011.
Iain Valentine, the RZSS's Director of Giant Pandas said : "We are now able to predict that the important 36-hour breeding window when both pandas are likely to meet is imminent.
"Scientific results alone would suggest the day is just less than 10 days away; however, as Tian Tian's behavioural changes are coming in so strongly, we cannot rule out that the key 36-hour window may be much sooner.
"Every individual giant panda is different and this is only the second time Tian Tian has come into season in Scotland, so it is difficult to make a precise prediction at this stage.
"When the 36-hour window is here, Tian Tian and Yang Guang will meet several times to have the opportunity to mate and then, as Tian Tian finally ovulates and her hormones fall off, artificial insemination will also take place."
Zoo staff will be able to confirm whether there is a pregnancy in July or August, using ultrasound scans. Panda babies are usually born in August or September.
Tian Tian and Yang Guang are the first giant pandas to live in the UK for 17 years.
Tian Tian was born in Beijing in 2003, and has given birth to twins before, although she has yet to mate with Yang Guang.
Yang Guang is described as a “gentle giant” by zoo staff.
In the wild, giant pandas are in serious decline due to habitat loss. The creatures live in six mountain ranges in China - but with the destruction of lowland habitats, populations have had to move further into the mountains, dispersing the animals and affecting the birth rate.