Leeds are sitting just two points clear of the relegation zone, having not won in the league since early November.
However, a 5-2 FA Cup third round replay victory over Sky Bet Championship side Cardiff on Wednesday night lifted the mood at Elland Road.
Frank expects Sunday’s trip to West Yorkshire to be a stern examination of Brentford’s ambitions for the second half of the campaign.
“This league is the most crazy one. It is relentless and every game is so difficult,” Frank said.
“We are going to Leeds, one of the most difficult away grounds. They have very good fans, who make a lot of noise.
“The team play and perform much better than the results they have got. Leeds are the most intense runners so we need to be very aware of that.
“I understand why (Leeds manager Jesse) Marsch said that the Villa game is a ‘go-to’ performance (despite a defeat) – they looked such a threat and have players going forward who have pace and a big skillset.
“We need to be very well organised and we need to believe in ourselves.
“But we are on a good run and we need to use that confidence. Our attitude is that we are confident, but humble.”
Full-back Rico Henry missed last weekend’s win over Bournemouth with a minor calf issue but is expected to be available. Aaron Hickey, though, is rated as ‘touch-and-go’ to make the squad as he continues to recover from an ankle problem.
Former Leeds captain Pontus Jansson will not be fit to face his old club, while Shandon Baptiste and Frank Onyeka continue their own recovery.
Frank maintains the club are “very happy” with the squad after doing their January business early with the signing of Freiburg forward Kevin Schade, initially on loan.
“We are strong in every position,” the Brentford boss told a press conference. “If we find a hidden gem somewhere then, hopefully, we can get the player.”
Bees goalkeeper David Raya has been linked with the likes of Manchester United, Tottenham and Chelsea.
Frank, though, does not feel any of the squad will be distracted by transfer rumours.
“I always expect them to train well and do well for the club,” he said.
“David Raya really cares about Brentford and the team so I can’t see that him, or anyone else, isn’t doing everything they can to make sure we are doing our best.”