The Lions won the first test in Brisbane 23-21 last weekend and could wrap up a first series victory since 1997's trip to South Africa at the Docklands Stadium on Saturday.
Howley was a player on the 2001 tour, when the Lions won the first test and led at halftime in the second test at the same stadium only to lose the series 2-1 to the then world champions.
Irish centre Brian O'Driscoll, who also played in 2001 and starts on Saturday, had spoken to the squad about a squandered try chance in the latter stages of the first half of the second test, Howley said.
"Brian O'Driscoll has been hugely influential," Howley told reporters.
"I think his experience of 2001, you learn from those experiences and we spoke of those experiences yesterday. There was an opportunity just before halftime when we broke through but we didn't take it.
"That's what it comes down to on Saturday is being ruthless and clinical and when those opportunities present themselves, we've got to take them."
Howley said the veterans of 2001 had helped instill a sense of how precious the opportunity presented to them on Saturday was to the squad.
"(We) never had the opportunity again, they don't come round too often," the former Wales scrumhalf said.
"I think you can only look at Brian O'Driscoll, that was 12 years ago, a guy who's won Six Nations, Grand Slams, Heineken Cups, the one trophy that's missing is winning a Lions series.
"That's what he was talking about yesterday, just make sure we don't have any regrets over the next 24-48 hours. Make sure it happens the way we want to happen."
Howley said the coaches and senior players had attempted to eradicate any complacency in the squad derived from the breathing room they earned with victory in the first test.
"I think there's an attitude to go 2-0, that's what we've been talking about in the week," he added. "That's what Brian O'Driscoll said, you have to take that oppportunity.
"We're 1-0 up and we could put Australia to bed tomorrow night, that's our mindset."
Howley said the Lions were expecting the Wallabies, who made two enforced changes to the backline after the first test, to come out firing on Saturday.
"Backs against the wall, wounded Wallaby, they're going to come out and play," he said.
"High risk, high reward. You talk about 80 games of one minute, that's the concentration levels you'll need.
"There're going to be key moments on Saturday and it's going to be about the side that takes the opportunity, that's test match rugby."
Despite bucking the "old adage" that you do not alter a winning side, the Lions made five changes to the team that won the first test.
Howley, though, thinks the 23 players in the matchday squad have proved they are ready for the huge challenge that lies ahead.
"In the hurly-burly of the battle, the emotional maturity, the decision-making, being accurate, that's what test match football is about," he said.
"The side that we've selected, we feel we've got test match animals that have made those decisions in games and understand what is required tomorrow night. I just hope we're right."
Despite his confidence in the players, Howley said he had been encouraging them not to think about the bigger picture.
"If you dare to dream it turns into a nightmare," he said. "I think the players have been very task-oriented this week and... that's what they've got to do tomorrow night, you focus on your job every thirty seconds.
"Because if you think about what you're going to create or what possibly is in the future, that doesn't happen."
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