After being humiliated by basement outfit Swansea and then dumped out of the FA Cup by West Brom last weekend, Klopp is desperate to avoid a third straight defeat tonight.
Wagner, whose Terriers famously beat Manchester United at home in October, senses the frailties in a Reds backline which has frequently undermined their bid for silverware.
Wagner said: “We have seen West Brom beat Liverpool in a comfortable way, to be honest.
“I was very impressed with what they have done at Anfield which is not the easiest place to go.
“Liverpool have lost last two games in a row and look vulnerable at the minute.
“Does that mean we will be successful? No. Does it mean we have a chance? Absolutely.
“If there is a chance, we will be there to take it. This is always how we go into games in the Premier League.”
Wagner knows the odds are stacked against Huddersfield as they bid to cause an upset against his fellow German to boost their survival prospects.
After a run of six league games without a win, the Terriers are wobbling alarmingly and sliding down the table.
Wagner, whose close friendship with Klopp began as team-mates at Mainz in the early 1990s, admitted: “We expected this to happen.
“We had a similar period in November and we turned it because we were focused on ourselves.
“This is exactly the same as we do now. We have a great opportunity in front of our home ground which we have and which we like to use.
“This is for sure we should not get carried away too far after this period where we didn’t get the results we wanted to have.
“To beat Liverpool, a lot of details have to go in our favour.”
The Huddersfield boss, who has attended games at Anfield with his family as a guest of Klopp, was best man at the Liverpool manager’s second wedding.
Klopp, meanwhile, is godfather to Wagner’s youngest daughter Lynn and the Liverpool boss appointed Wagner as coach of Borussia Dortmund’s second team in 2011 before both men took jobs in England in 2015.
Asked about their close bond, Wagner admitted: “Of course it is different and special – we have a friendship and relationship which is extraordinary.
“We are always speaking; about the Premier League, opponents, players.
“Sometimes we play opponents they have played a week before or the other way round.
“But this week, we do not speak – tonight, 8pm, it is all about Huddersfield Town and Liverpool Football Club.
“We are both in a situation where we need the points – Liverpool can have all the points they want in the Premier League – just not the ones tonight.
“We will try everything – fight for every yard to cause them the biggest problems they can ever have.”