Jets striker Rose will return from a calf injury and line up against Sydney FC at McDonald Jones Stadium on Saturday in the second leg of their semi-final tie.
The 27-year-old goalscorer was expected to play in the first leg after being rested from the club's F3 derby win in the final regular season round.
But coach Mark Milligan opted for caution, with the Jets then salvaging a 1-1 draw at Allianz Stadium last week thanks to Eli Adams's 58th-minute equaliser.
Sky Blues striker and former Jets player Apostolos Stamatelopoulos had opened the scoring in the 50th minute.
Now one game away from punching their ticket to a grand final, Milligan is backing Rose to go full throttle.
"He's back to his very best," Milligan said.
"That's why we sort of made that decision to give him that extra week as well.
"It's not just him, but we know a number of them play that high-intensity brand of football, and that's a part of who Lachie is.
"That's why that sort of extra week was good because it gives him the confidence as well to go out, and if he gets the opportunity to be himself."
The Jets have been given another timely boost, with midfielder Lachlan Bayliss earning a World Cup spot in New Zealand's 23-man squad.
"It's a very close group. Everyone feels the ripple effects of these kinds of things," former Socceroos player Milligan said.
"It's a massive privilege, and it's good because it brings to light everything that I've been preaching to them as well.
"That if they work hard, then opportunities will come."
Unlike Rose, Sydney FC's superstar striker Joe Lolley remains underdone.
Lolley made his return from ankle surgery in the 1-1 draw but played just 13 minutes as a second-half substitute.
It was the 33-year-old's first match since March after undergoing surgery for a syndesmosis injury.
Asked if Lolley is a chance of starting, Sky Blues interim coach Patrick Kisnorbo said: "Emotionally, you'd probably say yes.
"You've got to be realistic as well, knowing where he's come from.
"If you ask the player, he'll probably always say that they'll be able to start because it'd be great.
"For me, it's a balancing act."
Should Newcastle defeat Sydney and reach the grand final, they will be one victory away from pulling off an unprecedented domestic treble.
The Jets won the Australia Cup in October before winning the league for their maiden premiership.
Central Coast were the last side to pull off the league double, which completed an international treble with their AFC Cup title.
Adelaide United and Auckland FC play in the other semi-final at Coopers Stadium on Friday.
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