South Africa slipped to a 19-0 defeat to New Zealand in Johannesburg and Deans knows Peter de Viilers and his squad will be determined to avoid another home loss.
"Without a doubt, the Springboks won't want to suffer again at home," Deans told The Australian newspaper after watching the match at Newlands.
"It's hard for the Springboks now to win (the Tri Nations), but hence their likely response as a result.
"They are world champions and there is no way they will be excited about contemplating another loss."
Deans has already led his adopted country to victory over the Boks in this year's Tri Nations but, having witnessed a hugely intense and competitive match on Saturday, the Kiwi knows the Wallabies will have to be at their best if they are to record their third win of the tournament.
"Being an observer in the arena, it was very evident that any side that enters a Tri-Nations fixture that is not at full noise is just going to get belted," said Deans.
"It was great to be there. It was great to be able to witness it live. The score appears to be one-sided but the contest itself was very much anything but that.
"And the first half was probably the biggest indicator of that. There was an awful amount of rugby played in that first half, but there was very little to show for it. It was 5-0 on the scoreboard at half-time.
"The All Blacks got home and they played well. They absorbed the pressure and there was a significant amount of pressure from the Boks.
"There were times they survived on defence when there was probably no other side in the world that would have because the Boks did bring a lot of pressure to bear and it looked on occasions like scoring was inevitable, but they hung in there and they defended very well.
"Both sides had a huge intensity. It was only late in the game when the game got away from the Springboks that they were forced to play a game that they weren't really that comfortable with and it cost them."
Australia and South Africa go head-to-head at the ABSA Stadium this Saturday (kick-off 2.05pm BST) before facing each other once more at the same kick-off time the following Saturday in Johannesburg.