The 21-year-old was elevated to the starting line-up for Friday's sudden-death clash in Hamilton after slotting a winning 48-metre penalty off the bench against the Waratahs in round 15.
The Reds will have to make history if they are to make it through to the semi-finals.
No Australian team has ever won a play-off in New Zealand, although the Queenslanders scored three tries to two over the Chiefs when they fell to them 29-20 in last year's quarter-final in Waikato.
Lynagh missed two conversions and a penalty as he was out-kicked by the Chiefs' Damien McKenzie.
Reds No.8 John Bryant, lock Ryan Smith and prop Jeffery Toomaga-Allen have also been promoted to the starting 15, while incumbent No.10 Lawson Creighton will provide some extra spark off the bench.
"Tom's finals experience last year pays forward for us. With Lawson from the bench, it's a combo that's worked well for us this season," Kiss said.
"I'm very confident in the job they'll do."
Carter Gordon is back for the Rebels' first - and possibly last - Super Rugby Pacific final. (James Ross/AAP PHOTOS)
Melbourne are back to full strength, with the exception of injured lock Lukhan Salakaia-Loto, for their daunting trip across the Tasmanto tackle the Hurricanes.
Playmaker Carter Gordon returns after two matches sidelined following a head knock, while winger Lachie Anderson has also overcome concussion symptoms with Andrew Kellaway shifting to fullback.
The table-topping Wellington side raced out to a 33-7 lead by halftime in their last clash, with Rebels coach Kevin Foote naming Test propTaniela Tupou in the run-on side to help his team get on the front foot.
"We understand how important the start of the games are, especially against New Zealand teams who come with incredible intensity earlyon," Foote said.
"It's about matching that, don't get shocked by it and then try and react, that's the most important thing."
With their first ever final possibly their last after being told by Rugby Australia last month they will be shut down at season's end, Melbourne will hold an open training session on Thursday, encouraging fans to turn out and show their support.
"We've changed things up this week because it's finals and we want things to feel different," Foote said.
"We're not just happy with being the greatest Rebels team of all time we actually want to do something special and this is what history isall about, sport gives us this opportunity."
The Brumbies were once again the benchmark Australian side in the competition and were rewarded with a home quarter-final against the Highlanders for their third-placed finish.
Test props James Slipper (calf) and Blake Schoupp (shoulder) are both out, so Harry Vella has been handed the No.1 jersey after playing 78 minutes against the Western Force last week.
In better news for coach Stephen Larkham, No.8 Charlie Cale returns to the starting line-up from injury, with Nick Frost making way.
"It was a tough decision and we sort of weighed it all up. But we just felt that Charlie had been doing a really good job for us all year and that this is going to be the best combination for this weekend," Larkham said.
