Jockey Luke Nolen gave the nation a heart attack when he tried to give the star mare the easiest of times over the last 100 metres. As his rivals went under the whip, Nolen appeared to sit up with 75 metres remaining.

It was only in the last couple of strides he realised the unbeaten mare could get beaten and pushed hard to hold off French second favourite Moonlight Cloud and Restiadargent.

A huge cheer went up in Melbourne's Federation Square at the moment the people's champion crossed the line. Following a series of nerve-wracking replays, the result was confirmed and Black Caviar's first sojourn on to foreign soil ended with victory.

The sight of Nolen appearing to ease up short of the finishing line provided a further twist to an already dramatic race.

After Nolen jumped well and positioned himself just off the lead, he started his run at the 600-metre mark.

Black Caviar took the lead with 200m remaining and looked home before Moonlight Cloud and Restiadargent began to move up on the inside.

With all those watching holding their breath, the winning post came just in time to preserve the three-year-old star's perfect record.

The sight of Nolen appearing to ease up - perhaps mistakenly thinking he had already reached the winning post - short of the finishing line provided a further twist to an already dramatic race.

''I underestimated the testing track. I tried to shut her down,'' Nolen said after the race.

''It was brain fade … but I just got it wrong.''

Trainer Peter Moody let out a big sigh of relief. ''You only have to win by a quarter of inch and we got the job done,'' Moody said.

Timeform is expected to lift Black Caviar to 137 or 138, making her the highest rated mare in history after the win, surpassing Allez France, the French champion of the 1970s, and England's great sprinter of the 1980s, Habibti.

She received the royal seal with the Queen making a special trip to the back of the royal box to watch Australia's racing queen parade. When Black Caviar stepped on the hallowed turf she was greeted by roar from the crowd, which is usually reserved for a winner returning.

The Queen came down into the parade ring to pat Black Caviar before giving her owners the trophy.

Instead of the unchallenged runs to the line the Australian entrant encountered during much of her unbeaten run Down Under, the world's No.2 rated horse was pushed all the way before scoring by a nostril from Moonlight Cloud and Restiadargent.

Black Caviar's run couldn't have been in greater contrast to the run produced by the British star Frankel earlier in the week.

A magic week at Ascot started with the unbeaten Frankel's 11-length romp in the Queen Anne Stakes on Tuesday. So You Think had given an Australian victory of sorts in the Prince of Wales Stakes on day two, Frankie Dettori returned to his best on Colour Vision in the Gold Cup on Wednesday, while the highlight of day four was the Queen winning her first race at her meeting since 2008 with Estimate.

It was Australia day at Royal Ascot with the most popular fashion accessory to the top hat and tails, salmon ties with black spots, the Black Caviar colours. There were close to 10,000 Australians to cheer home the mighty mare.