Halfpenny, who kicked 48 points in five RaboDirect PRO12 games last season for Blues, will be looking to lead his country to their first victory on Australia soil since 1969 after Mike Harris' late penalty denied them in Melbourne.
But Howley, whose only change comes on the bench withKen Owens replacing Richard Hibbard as the reserve hooker, admits they need to make it count in Sydney this Saturday.
"We know what we have to do to beat Australia, but there is a difference between knowing how to win and achieving that aim," said Howley.
"This Wales team was within around 30 seconds of beating the Wallabies on their home patch for the first time in 43 years.
"The challenge now is to go one better than that and make sure we are ahead on the scoreboard, not just when the hooter goes but when the game finishes this weekend.
"The players can take some credit for the way they played for the large part of the match on Saturday, but that will be scant consolation if we don't come home with a win in this series.
"We have risen to our highest position [fourth] in the IRB World Rankings because of our performances so far this season, which can have positive repercussions for the 2015 Rugby World Cup.
"But now we want to stay there and that means coming away with the spoils on Saturday afternoon."
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