The Socceroos went down 3-2 against world champions Germany after a battling display in their Group B opener in Sochi on Monday, while the Indomitable Lions were beaten 2-0 by Chile in Moscow.
The defeats have left both the 2015 Asian Cup winners and current African Nations Cup holders with little margin for error if they are to extend their stay in Russia for the knockout stage.
Degenek, who plays his club football in Japan at Yokohama F. Marinos, feels Ange Postecoglou's men have what it takes to deliver the required result at the Krestovsky Stadium on Thursday.
"It is a must-win game for both of us because we both lost our first games," the defender said to FFA TV.
"A win for us means we go on against Chile and win that and we are into the semis.
"Against Chile, they (Cameroon) were sitting back and hitting on the counter attack. They are very, very direct and very quick.
"I expect them to be very physical, very present and attack-minded, so I am expecting a lot of transition, fast football, a lot of breaks."
Degenek added: "They won't underestimate us - they will see from our second half against Germany that we are a team that plays a lot of good football.
"They will be prepared for us and we will be prepared for them as well."
Cameroon will come up against Australia for the first time in international football and are then set to face Germany in Sochi for their final group fixture on Sunday.
Coach Hugo Broos understands the challenge which is in front of his side, who never really got going in their opening match.
"Australia play with a lot of fighting spirit and I expect a difficult game against a team with a different style to Chile," he said at a press conference.
"We will have to be at our top level, because if we lose we are done at this tournament."
