"I like the pool," Gregan said as he paraded the Webb Ellis Cup around Sydney Harbour as an ambassador for Emirates Airline.
"It's great to play tough rugby at a World Cup, at least one or two tough pool matches to prepare you for what's ahead.
"Because what's ahead of you is three knockout games and you've got to be prepared for that because the quarter-final is probably the most difficult game in a Rugby World Cup.
"It doesn't matter what your squad looks like on paper, if you're a little bit off emotionally or technically or you're maybe ahead of yourself in a quarter-final, then you don't continue."
Gregan said it was critical to peak at the business end of the seven-week tournament and pointed to France's history of dropping pool games yet qualifying for three World Cup finals as evidence.
But he admitted peaking come finals time was easier said than done.
"If everyone knew the key, there'd be a lot more winners on that trophy. It's not that easy," Gregan said.
Above all, Gregan says the team that lifts the trophy will have benefited from refereeing decisions, flashes of individual brilliance and luck with injuries.
"Any team who has won the World Cup and said they didn't get a bit of luck along the way, I think they've got pretty short memories," he said.
"In 1999, we were a chance of missing out and then Stephen Larkham kicks a field goal [in the semifinal]. I think he kicked two in his whole career.
"Jonny Wilkinson did what he did against us in 2003, but England could have been out the back door against Wales in a quarter-final.
"And again last World Cup, New Zealand beat France 8-7 [in the final]. It was a penalty kick by [Francois] Trinh-Duc, who could have knocked it over from 45 metres out and it's a different ball game.
"So you need a bit of luck along the way. You need a good, healthy squad and you need incredible belief and preparation, that's for sure. But a bit of lady luck always helps."
- AAP