The Ulster second row is hoping to force his way back into the Ireland starting line-up for next week's Series finale against Argentina.
With Mike McCarthy having put in a man-of-the-match performance against the Springboks and Donnacha Ryan also impressing, Tuohy knows he has to deliver against the Fijians.
"Mike was selected ahead of me last week and then he had a great game, which is just one of those things," he said.
"For me to do Mike justice is to have another good game against Fiji, push him forward. The competition will push me on and also push him on and will really benefit Ireland.
"Donnacha Ryan also played well (against South Africa). People go on about there being no competition in the second row but I think there is."
Tuohy will enjoy the experience of facing the unpredictable Fijians, but is mindful of not becoming too unstructured and being lured into the sort of 'loose' game that the tourists thrive on.
"It's very much chalk and cheese really. They're extremely loose, unstructured, massive hits going in all over the place.
"They're great ball carriers, and there's not a great deal of regard for any structure in their game. Sometimes people look to take Fiji on at their own game but if you try that, you could come unstuck."
The 27-year-old, who recently agreed a two-year contract extension with Ulster, would love to play his part in a Thomond Park triumph this weekend.
He has yet to taste victory in an Ireland jersey at senior level - indeed, four of his five caps to date have come against New Zealand.
Tuohy has won with the Ireland Wolfhounds against Tonga and Scotland 'A' previously, but his record for Ireland XV in uncapped games shows three defeats - two against the Barbarians (2010 and 2012) and one to the New Zealand Maori (2010 summer tour).
With a nod to this year's summer tour to New Zealand, he explained: "Four of my five caps have been against the All Blacks. I don't go for the easy ones! The other was against Australia.
"It is tough. New Zealand are a fantastic side and I would have loved to have been part of the first Ireland team to beat them, we went close in that second Test.
"It was disappointing as tours are based on results but, personally speaking, the three starts were good."
There will be Park & Ride facilities in operation for the Ireland XV v Fiji match on Saturday, at the following locations:
- Kilmurry Lodge Hotel, starting from 2.30pm
- Radisson Hotel, Ennis Road, starting from 3.30pm
- South Court Hotel, Raheen, starting from 3.30pm
- Woodlands Hotel, Adare, starting at 4.30pm
There will also be a Public Bus Service running from Henry Street in Limerick city centre, starting at 3.30pm.