Christiansen’s team led the division in September after seven victories and two draws from their opening nine games, but a torrid run left the pressure on the Dane ahead of Saturday evening’s visit to in-form Brentford.
Christiansen had admitted earlier in the week that the clash at Griffin Park was a fixture United needed to win, although the head coach then received the support of chairman Andrea Radrizzani who declared: “We are building a solid project – and I believe in my team.”
But Leeds encountered yet more problems in west London as an entertaining game featuring two major goalkeeping gaffes was settled by late strikes from Yoann Barbet and Ryan Woods.
The defeat left Leeds 10th and just one point above 15th-placed Queens Park Rangers, but Christiansen vowed to fight on after the international break.
“There’s only one way – to continue working hard,” he said. “We need to come out of this situation.
“I know it’s the same question from the last few weeks, but if we don’t have faith, if we don’t believe, then we can throw everything away and go home.
“We are here, we are fighters and we’ll come back again.
“All of these situations will be hard. There’s more pressure now and if we lose the next game then there’s more pressure. This is the business of football. We all know how it is, but there’s only one way to come out – stick together and fight back.”
Dominant Brentford took the lead in the 22nd minute when Whites goalkeeper Andy Lonergan dropped a cross from Romaine Sawyers to allow Neal Maupay to head into an empty net.
Brentford’s Ollie Watkins then blazed a late first-half penalty over the crossbar after Pontus Jansson had fouled Maupay.
Leeds improved after the break and levelled seven minutes after the hour when Daniel Bentley mirrored the antics of Lonergan and failed to collect a cross from Gaetano Berardi with Gjanni Alioski this time the beneficiary.
But a Brentford side who hit the crossbar twice in the second half condemned United to a seventh defeat of the season as an 85th-minute free-kick from Yoann Barbet dipped under Lonergan before Ryan Woods wrapped up the points.
Christiansen added: “They are not fighting for me, they are fighting for themselves.”
Leeds United: Lonergan, Ayling, Cooper, Jansson, Berardi, O’Kane (Hernandez 45), Phillips, Vieira, Alioski (Grot 80), Saiz, Lasogga (Roofe 45). Unused substitutes: Wiedwald, Shaughnessy, Dallas, Sacko.
Brentford: Bentley, Bjelland (Mepham 45), Jozefzoon, Yennaris, Maupay (Vibe 80), Watkins, Egan, Woods, Sawyers (Mokotjo 73), Clarke, Barbet. Unused substitutes: Daniels, Macleod, McEachran, Canos.
Referee: Stuart Attwell.