It's been a long day! Giant Panda Tai Chan takes a doze in the midday sun.[cctv.com]

It was a perfectly executed forward roll - even better for the fact that this panda managed it in his sleep.

The animal, called Tai Shan, was sitting in his zoo enclosure when he began to doze off, his eyes flickering open and shut before he succumbed to sleep and slumped forward.

The sleepy panda could have fallen flat on his face. But instead he popped his head between his legs and turned head-over-heels before landing on his back.

If pandas can look surprised, then four-year-old Tai Shan certainly did at that moment.

Tourists at the National Zoo in Washington DC, who saw the four-and-a-half-year-old panda roll off the kerb only to recline in the grass, were delighted by his impromptu gymnastic skills.

The classic moments were caught on camera by visitor Judy Young, 61.

Tai Shan is the only panda born at the zoo that has survived.

His parents Mei Xiang and Tian Tian were donated to the zoo by the China Research and Conservation Centre for the Giant Panda in Sichuan Province.

His mother was artificially inseminated in 2005 after natural mating between her and Tian Tian failed.

After Tai Shan, whose name means Peaceful Mountain, was born in July 2005, the conservation centre issued 13,000 free entry tickets for people to see him.

The tickets were all snapped up within two hours and some sold on eBay for as much as ￡300 each.