The 28-year-old, a summer signing from Newport, helped Caley Thistle to a 2-2 draw at Tynecastle last weekend having been two goals down at half-time. He now hopes that the confidence generated from that can be displayed this afternoon.
The defender said: “You look at last Saturday and the way we performed, down to ten men, the boys really had to stick together and showed true fighting spirit. It was encouraging last week to come away from a difficult ground to get ourselves a 2-2 draw.
“I think if you look at the boys we’ve got in the changing room, there is always belief. I think we’ve got so much energy and a youthful side. Going down to 10 men I don’t think fazed us, to be honest. We were more determined to get a result, so in terms of the belief we have got in the side, it’s a credit to the boys last week.”
Inverness take on Celtic at the Caledonian Stadium in the lunch-time kick-off.
Neil Lennon’s side return to SPL action after securing a 2-0 away win at Helsingborg on Tuesday in the first leg of their final Champions League qualifier.
Warren said: “It’s one of the first games you look out for on the fixture list, for me. Obviously, they are one of the biggest clubs around. For me, personally, it is going to be a real test and for the lads, it will be a test. But it’s not a test we fear or are fazed by.
“I think we are more looking forward to putting ourselves against the best.”
Warren admits he is surprised by the pace of the game in Scotland, compared to the Blue Square Premier.
He added: “I’ve just noticed the quickness and tempo of the game. Especially looking at last Saturday, you look at the wide players and forwards, it’s not a case of them standing still.
“There is a lot of movement involved and, as a centre-half, you have to be totally focused and mentally prepared from the first minute.
“From what I’m used to down in the Conference in England, it’s more direct and back-to-front quite quickly.”