Andre Villas-Boas has backed young Ryan Bertrand to fill the void left by Ashley Cole for Chelsea's Sunday showdown with Manchester United.
Chelsea will be without left-back Cole for the first time in 65 Premier League matches for the clash with the champions.
Cole was sent off against Swansea in midweek and the pressure is on Villas-Boas with John Terry - and possibly Frank Lampard - also missing Sunday's game.
Villas-Boas faces a decision whether to switch Jose Bosingwa to left-back or put his faith in Bertrand and the Chelsea boss offered his support to the 22-year-old Englishman.
"We have full trust in Ryan's abilities," said Villas-Boas. "It's a game of massive importance based on recent results and the fact that we have Man United, the champions, at home.
"Difficult decision to be made (on Saturday) when we practice strategically for the game."
One of those decisions is likely to concern Lampard, who has missed the last two matches with a calf problem and did not train on Thursday.
"Lamps has a chance to make it to the game," added Villas-Boas. "Again, reassessment (on Saturday) to make a final decision."
Villas-Boas confessed he is still struggling to come to terms with September's controversial defeat at Old Trafford, which was his first league loss as a manager for almost 18 months.
"I try to forget it but I can't," he said of the game where United scored two goals that should have been ruled out for offside.
That defeat appeared to be the catalyst for a slump that has seen Chelsea fall 12 points behind the Premier League leaders.
But the Portuguese coach knows it will take more than one victory to get his team back on track.
When asked about the consequences of a win, Villas-Boas said: "Good maybe in the immediate but maybe a false message regarding the future. The future has to be continuity.
"After Man City, we went to seven points behind and we didn't find that continuity that would've taken us closer to the leaders.
"So it can have an extra importance only if you manage to get the continuity after that."