Chelsea’s interim head coach, Calum McFarlane, admitted the opening 15 minutes of his side’s home defeat by Nottingham Forest were “not acceptable” as Chelsea lost a sixth consecutive Premier League match for the first time since 1993.

A second-minute header from Taiwo Awoniyi was followed by an Igor Jesus penalty in the 15th minute to leave Vítor Pereira’s second-string side able to keep their hosts at arm’s length throughout the contest. Awoniyi’s second later in the game ultimately sealed three crucial points for Forest in their battle against relegation.

“I thought the first 15 minutes we were nowhere near the level we needed to be,” McFarlane said. “The early goal was a bit of a sucker punch. We know that they like to cross to the back post. We know that the No 9 likes to peel to the back post. We should defend that moment better.”

Chelsea had opportunities, with Enzo Fernández hitting a post, Cole Palmer missing a penalty and João Pedro having a goal ruled out for offside before the Brazilian finally scored a spectacular scissor kick late on. “We had our moments,” said McFarlane. “When you start that badly, you need those moments to go your way, to give you a chance to fight back into the game. But ultimately, the first 15 minutes was not acceptable.”

Chelsea are 10 points off the fifth place that would guarantee Champions League football with only nine points to play for. Asked if Chelsea’s players would be sufficiently motivated to pursue qualification for the Europa or Conference League, McFarlane said: “I know the group. I’ve known them for a little while now. They are driven. They want what’s best for themselves. They want what’s best for this club. We’re going to do everything we can to try to win every single game we can from now to the end of the season.”

Pereira can now focus on a Europa League semi-final second leg against Aston Villa, though the Forest manager has concerns over Morgan Gibbs-White, who was forced to leave the field after sustaining a heavy cut after entering play as a substitute.

“He has a deep cut and we’ll see but Gibbs-White is a fighter,” Pereira said. “I hope our medical department can do magic to put him in the right condition, because he is important for us.”