The back row has won plaudits for his big role in the comeback on home soil, but insists the home fans deserve real praise for the unwavering backing they gave the team until the final whistle and for never losing the faith.
"The noise from the fans was the loudest it has been all season and it resembled some of our biggest matches here in previous years," said Horstmann.
"They stuck with us throughout the whole game and were very loud in those last few scrums when we needed them. They were instrumental in getting us through such a dramatic end to the game.
"It gives you a huge lift and real belief when you have that level of support and home advantage is massive. Our fans are certainly one of the most vocal around and really get behind you.
"It means a huge amount to all the boys and we are very appreciative of it. We can't thank them enough and they played a big role by staying with us on Sunday.
"Sunday was a day to learn lessons from and we certainly don't want to go through that emotional rollercoaster again - I'm sure the fans don't want to go through it again.
"I believe it has given us a good shake-up and I'm sure we won't put our supporters through that in the second leg of the final at Sixways."
Worcester now face a trip to the Mennaye Field in Penzance for the first leg of the final on Wednesday (May 11) and Horstmann is only too aware of the size of the challenge the Warriors will face.
"We're itching to put the wrongs of the weekend right - but we know how tough it is going to be," he added.
"We have had two very close encounters with Pirates and they are a very strong side, especially down in Cornwall where they are hard to beat so we are up against it.
"We have done a lot of homework since Sunday and we know we have got a really tough challenge, but we are looking forward to it and just pleased to now be in the final.
"It was amazing the last time we went to Pirates and saw such a fantastic turnout and effort by our fans to be there. We hope as many of them can make the trip down there again and we hope to put on a good show."
Tickets remain on sale for the second leg of the RFU Championship final at Sixways Stadium on Wednesday, May 18 (kick-off 7.45pm). Call the Warriors Box Office today on 01905 454183 or click HERE to buy online.