Italy won their first two pool games, while the Springboks suffered a 23-13 defeat to New Zealand in their opener and followed it up with a 57-3 win over Namibia.
The loser of this match is likely to finish third in Pool B and miss out on a play-off spot, and O’Shea and Bok coach Rassie Erasmus emphasised the importance of producing a strong performance up front.
“If you don’t front up physically against South Africa, you’ve already lost the match. You must take them on in the forwards. We must treat it like the last match we’ll ever play,” he said.
“The momentum can swing in a moment of magic or a penalty and we have to be competitive. You need to be at your best throughout the match because you never know when that swing will come. I’m sure the lads will give their all on Friday.”