"How is Guy letting Chynna chose her own song fair? Pretty clear Guy is pushing for her to win," one person tweeted.
Another wrote: "So Mitch and Jack were told what songs to sing by Guy yet Chynna got free [rein] to sing what song she wanted too? Sounds like favouritism to me."
"Don't bring Guy back," wrote another.
In fact, Twitter users were claiming that Guy and other judges had made "really poor" song choices for their team members.
Jack Vidgen performed Calum Scott's "You Are The Reason" while Mitch Paulsen sang a reggae version of Post Malone's "Better Now". Chynna sung "Jolene" by Dolly Parton.
The other two contestants that also left the show in the semi-finals were Sheldon Riley from Team Delta, and Lee Harding from Team George.
The upcoming finale week will include contestants Zeek Power, Daniel Shaw, Jordan Anthony and Diana Rouvas.