"We were unlucky last time against the Ospreys and hopefully we can put that right," said Turnbull.
"These are really big games, the standard is right up there and they're real full-blooded games. We have to front up and be physical."
The Ospreys boast a wealth of riches in the back row and present a daunting challenge but Turnbull is aiming to keep Jerry Collins and co quiet.
"The Ospreys have got some big characters in the back row and hopefully we can keep those boys under wraps," added Turnbull.
"Collins and Marty Holah are formidable players who have been involved with the best team in the world in New Zealand.
"As a young guy growing up, World Cups, I was watching Collins running over people. I never thought I would be facing him in a Magners League game, but it helps to raise standards because he brings out the best in players.
"Jonathan Thomas has not got the amount of Wales caps for nothing and they have got a good young back rower in Justin Tipuric coming through.
"I have played with him and against him and he is another exciting prospect.
"They are full of internationals and have a lot of talent. They also have exciting and creative backline. But if we can neutralise them at first phase we will have a chance. We need a big effort from all 23 Scarlets' players."
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