Samoa have changed their halves ahead of a World Cup semi-final, naming Ronald Volkman at five-eighth after Chanel Harris-Tavita suffered a hamstring injury.
Four nations remain in contention, with Saturday's matches sending the winners through to the Final.
Australia meet Samoa at Allianz Stadium, where Dolphins teammates will represent opposing sides.
Dolphins outside back Jack Bostock is part of Australia's unchanged starting side, while Samoa will call on Hamiso Tabuai-Fidow, Connelly Lemuelu and Francis Molo.
Tabuai-Fidow recently extended his Dolphins contract for two years, keeping him at the club until at least the end of 2029.
He has threatened defences with his speed and footwork during the tournament, while Molo scored his first international try against Tonga.
Samoa are seeking a Final place after their 20-18 loss to Tonga, with Benaiah Ioelu starting at hooker and Deine Mariner returning to the interchange after a hamstring injury sustained in Round 1.
Earlier on Saturday in Newcastle, New Zealand face Tonga, renewing a rivalry that includes Tonga's 28-22 World Cup win in Hamilton in 2017.
New Zealand beat Fiji convincingly in the quarter-finals, and Dolphins hooker Jeremy Marshall-King will help their bid to advance.
Kalyn Ponga could return from the broken arm he suffered in the tournament opener against Australia, while Phoenix Crossland is available after a four-game suspension.
Tonga coach Kristian Woolf has named an unchanged 19-man squad after his side's victory over Samoa.
Dolphins players Isaiya Katoa and Kulikefu Finefeuiaki are included, with Katoa again named alongside Tui Lolohea after playing 80 minutes against Samoa on his return from an ankle injury.
The playmaker will be important to Tonga's attacking combinations against New Zealand, as Dolphins representatives feature across all four remaining nations.