By Karolos Grohmann

LONDON (Reuters) - Britain's gold medal hat-trick at the track and field events on Saturday was the greatest day in sport ever witnessed by London Games chief and two-time Olympic champion Sebastian Coe.

The host nation of the 2012 Olympics won three athletics gold medals within an hour to crown their most successful Olympic day for over a century, with two other golds coming in rowing and one in cycling.

Jessica Ennis triumphed in the heptathlon, Greg Rutherford won the men's long jump and Mo Farah clinched the 10,000 meter title in front of a mesmerized and ecstatic 80,000 crowd at the Olympic stadium.

"Up until last night the best moment was Magic Monday (at the Sydney 2000 Olympics) with Cathy Freeman winning and (Haile) Gebrselassie against (Paul) Tergat," said Coe, basking in the successful start of the athletics competition.

"This did edge ahead of it. There was a narrative of infectious success. It was the greatest day in sport I have ever witnessed."

A successful track and field competition will not only be a major boost for the London Games, it will also further vice president Coe's chances of becoming the next International Association of Athletics Federations president.

Coe, who still has to officially announce his candidacy to succeed Lamine Diack, said the current IAAF chief had told him that a successful athletics competition was his only mandate as vice president.

"I dreamt we would have a night like that but not in my wildest dreams did I think it could unfold like that," Coe, the 1980 and 1984 Olympic 1,500 champion, told a news conference.

"It shows that when you present sports as well as last night then track and field is as strong a sport as any in the world.

"When you present it well it is a very, very strong global sport."

Athletics is desperate to become more relevant to a younger generation and has been striving to make meetings more broadcast-friendly by cutting down the length of the sessions.

(Editing by Mark Meadows)