The 21-year-old Swede kept his cool to push the ball neatly past goalkeeper Robert Sanchez in the 48th minute after being put through by Taiwo Awoniyi following a Chelsea mix-up in midfield.

“We worked hard and defended well. When we won it back, I was quick enough,” Elanga said.

The hosts’ expensively assembled side had more than 75% of possession and spent much of the match buzzing around the Forest goal, passing in tight triangles or relying on surging runs from Raheem Sterling but failing to find the killer shot on goal.

Forest defended solidly, keeping Sterling and target man Nicolas Jackson tightly in check.

Chelsea coach Mauricio Pochettino still has a lot of work to do in gelling his side, who showed some quality but no ruthlessness. They had 21 shots but managed only two on target.

Senegalese striker Jackson failed to latch on to crosses from Sterling in the first half and spurned a golden chance to level the match when he chipped the ball over the bar after a goalmouth melee in the 82nd minute.

“Today I think we created chances but we were not good enough in the last third,” Pochettino told reporters.

“Of course we are disappointed because we made a mistake and we conceded,” he said, adding that the team had quality and would mature.

“We need to be positive, keep going. It’s about the process.”

Steve Cooper’s visitors celebrated wildly at the whistle after a battling underdogs’ performance.

Cooper said he was proud of the resolve and desire his side had shown.

“The mental challenge of the game I thought we were really excellent at,” he said. “If we want to get results like today…it comes from within.”

Forest’s three toughed-out points mean they rise to ninth in the Premier League table, two places above their wealthy London hosts.