Australia saw off South Africa (14-12) in a bruising Cup Semi-Final before Fiji staged a second-half fightback to take all 22 Sevens World Series points on offer (21-15) in another memorable Final.
After finishing runners-up in Sydney last month, Australia's Cup Final appearance in the USA was the first back-to-back tournament deciders it has reached since May 2010.
Qantas Australian Men's Sevens Head Coach Andy Friend said: "We'll take a lot out of this tournament and it's up to us to carry this momentum that we first gained in Sydney, and now Las Vegas, through to Canada and the rest of the series.
"Today's games were two physical encounters. In my opinion, in the Semi-Final, I didn't think we played our best football but we hung in there and managed to get the result. In the Cup Final, we wanted to move Fiji around a bit and managed to do that at various stages. However, credit to Fiji who took their chances in the second half."
Assessing the Australian Men's Sevens program, Friend added: "We're building depth in the squad and building a depth as well as our own game style. We know we have a lot of work to do though everything is headed in the right direction.
"Losing two Cup Finals in a row is disappointing but we are learning with every single game and must continue the hard work."
At a blustery Sam Boyd Stadium, Australia raced into a 15-point lead in the Cup Final against Fiji. Tries from Sam Myers, a long-range effort from Ed Jenkins and Cameron Clark had the Fijians on the back foot throughout a near-perfect first half from the Australians.
However, with the wind now wreaking havoc, Fiji hit back with 21 unanswered points of their own. Kitione Taliga (2) brought the islanders within touching distance of the Australians on the scoreboard before Quade Cooper was incredibly denied when looking set to score. From the ensuing knock-on, the ball found its way to Savenaca Rawaca who sprinted the length of the field to give Fiji the Cup.
Australia booked its spot in the tournament decider after a thrilling, last-gasp win over South Africa. Boasting Springbok legend Bryan Habana in its ranks, no quarter was given in a brutal first period.
Lightning South African winger Seabalo Senatla opened the scoring midway through the first half after a quick-tap penalty caught the Aussie defense off guard. The second stanza continued in much the same vein but this time Australia's spell of possession resulted in a penalty try being awarded after Quade Cooper was illegally denied the opportunity to dot down in the right corner.
With the try converted, Australia were leading but four consecutive penalties for the South Africans piggy-backed them up the field and Blitzboks skipper Kyle Brown scrambled over under the posts to hand the lead back to the Cape Town winners.
However, with the last play of an enthralling game, Allan Fa'alava'au danced through the opposition defense and offloaded to skipper Ed Jenkins. With the try-line gaping, Jenkins was taken out illegally with a head high shot by Rosko Specman and the match official had no option but to award a penalty try. Quade Cooper slotted the conversion from under the posts to hand the Australians an astonishing win.
Elsewhere in Las Vegas, South Africa claimed third sport by beating hosts USA (21-10) with New Zealand finishing fifth after a win over surprise packet Japan (27-7) to take the Plate Final.
The 2015-16 Sevens World Series heads north to a sold-out Vancouver for the inaugural Canada Sevens next weekend. Coach Andy Friend is expected to make several changes to the 12-man squad he will take to Canada.
The Blitzboks dominated most of the play but were punished by the referee, giving away two penalty tries to the underdogs in the second half.
Quade Cooper, who started off the bench in the windy conditions, almost cost his side their first try by failing to dive into the corner but Rosco Specman was adjudged not to have used his arms in a last-ditch tackle which put Cooper into touch.
Then trailing 12-7 after fulltime, Australia captain Ed Jenkins was taken high as he was racing towards the line, prompting the referee to award another penalty try which gifted Cooper a conversion in front to steal the win.
It's the second straight World Series tournament the South Africans have been knock out in the last four by the Thunderbolts, who also upset them in Sydney last month.
Australia play Fiji in the final after the Fijians beat USA 21-14 in their semi-final in the wet.
Andy Friend's charges swept aside the challenge of England (36-7) in Pool B before seeing off Argentina (26-12) in the Cup Quarter-Finals.
Qantas Australian Men's Sevens Head Coach Andy Friend said: "Yesterday I was really impressed with our ball carrying and our attack and today it was our defence that won the day. The boys worked really hard and backed each other up all the time.
"We had a couple of good performances against two very strong sides in England and Argentina. The boys are playing for each other and everyone understands their roles. It's simple, but effective."
On the Semi-Final clash against joint series leaders South Africa, Friend added: "South Africa have played well this tournament and are clearly a quality side. We had a good win against them in Sydney so we know we can get one over on them but we'll need to do everything right.
"We'll have to aim up physically, but there's also the technical side too. The ball carrying, being strong over the ball. We're all excited by the challenge ahead."
In the Cup Quarter-Final, Australia dominated the opening seven minutes with Argentina unable to cope with their opponents defensive shape and attacking verve. Brilliant ball control across the park involving Con Foley, Allan Fa'alava'au and Quade Cooper released skipper Ed Jenkins who scored the 98th try of his World Series career.
Allan Fa'alava'au added a second shortly after when he powered over on the left and Cooper released Sam Myers who extended the Aussies' advantage to 19 points at the break.
Dangerous winger Axel Muller reduced the arrears midway through the second period for the Pumas, but Myers capitalised on a period of broken play to confirm the win. Joaquin Riera pulled a try back for Argentina after the siren but it proved no more than a consolation for the South Americans.
Australia earlier had rounded out pool play with a polished 36-7 win over a beleagured England outfit. Cameron Cowell's chip and chase gave the English an early edge but from then on it was all Australia.
A delicate kick from Tom Kingston found Henry Hutchison to dot down before Kingston himself bustled his way to the try line after a series of penalties. The Aussies entrenched themselves in opposition territory for all of the second period and tries from Hutchison, Pat McCutcheon, Quade Cooper (his first in the Sevens World Series) and Ed Jenkins were just reward for a complete display.
The other Cup Semi-Final at the Sam Boyd Stadium tomorrow morning will see world champions Fiji take on hosts USA in what promises to be another mouthwatering tie.
Day One
Quade Cooper has made his long-awaited debut for Australia in sevens rugby, as the Thunderbolts demolished Scotland and Japan on day one of the Las Vegas Sevens on Friday.
Cooper, 27, came on as a substitute with just under five minutes left against the Scots, but his first few touches of the ball resulted in wayward passes as he initially struggled to adjust to the shortened format.
The Thunderbolts still scored a 26-0 win, but another "no look" pass from Cooper failed to go to hand in the later 33-5 victory over Japan.
It wasn't all bad news - Cooper did notch his first points against Japan with four conversions.
Cooper, who has represented the Wallabies 58 times in the 58-man version of the game, is expected to be a key component of Australia's bid for a sevens medal at the Rio Olympics.
"It was so pleasing that Pat (McCutcheon) could get 14 minutes under his belt against Japan while Quade felt a lot better in that second game too," Australian coach Andy Friend said.
"However, we need to keep this momentum going. First up (tomorrow) we have an England team that will no doubt come out firing after what was a tough day for them.
"We'll then have a quarter-final against either Fiji, Argentina or Samoa. Anything can happen."
Australian Rugby Union and AAP