Chelsea now sit seventh on 48 points, having been overtaken by Brighton on 50 following their 3-0 loss to the Seagulls which led to the sacking of Liam Rosenior this week.
The Blues have now lost each of their previous five Premier League fixtures, all without scoring and McFarlane will hope to try and steady the ship as he steps in once more to try and salvage the season.
What has gone wrong at Chelsea?
McFarlane, who reports state could manage the side until the end of the campaign, first spoke on what has gone wrong at Chelsea.
"It's not my place to say what's gone wrong. My full focus is on Leeds, we've got a massive game on Sunday. All I'm thinking about is preparing for that game.
"We haven't had a clear-the-air meeting. We've got the group focused on Sunday. It's really important we have a real focus for the game on Sunday.
"We definitely need to improve the performance, it wasn't good enough vs Brighton, we know that. We need to figure out the reasons why and make sure the group are in a better place for Sunday.”
McFarlane has a great relationship with the squad
McFarlane took charge of clashes against Manchester City and West London neighbours Fulham when Enzo Maresca was sacked last year. He leads the side once more, a side he says he has a very good relationship with.
"I have a really good relationship with the players. Our process will be the same as the last time I was an interim.
"We've spoken to the group about the remaining games and what's still to play for. Everyone is united. We want to win every game from now until the end of the season.
"Yeah, of course (Players must take responsibility), they're on the pitch - they're top players that can perform at the highest level and that hasn't happened for some reason. We need to move on.”
Finally, McFarlane commented on Estevao who was forced off during Saturday's 1-0 home defeat by Manchester United after he pulled up with a hamstring injury.
"Estevao unfortunately won't play for us this season. He is going to be out for a little bit of time. We're here to support him. Joao (Pedro) and Cole (Palmer), they trained, they're in a good place. We don't know yet, we'll make a call tomorrow."