Under-pressure Nottingham Forest boss Aitor Karanka believes the speculation over his future "wasn't the best" for his players after they slipped a 1-0 defeat to Millwall at The Den.

Former Manchester United midfielder Ryan Tunnicliffe's overhead kick gave the Lions their second successive Sky Bet Championship win while also stretching the visitors' winless run to five matches.

The defeat for Forest, who also wasted a three-goal lead to draw 3-3 with Norwich on Boxing Day, will only add fuel to the fire over mounting speculation that Karanka might lose his job.

And while the Spaniard welcomed the vocal support from the 2,200 fans who travelled to south London, he admitted the rumours about his future were counterproductive.

"The first half we weren't ourselves," said the 45-year-old, who was appointed in January 2018. "We didn't play with our intensity, we tried to do things we don't normally do.

"I think we have to try to recover as soon as possible and Tuesday we have another big challenge. The last 24 hours for us wasn't the best atmosphere for us to prepare the game.

"Maybe when I played 15 years ago you could arrive at this game without hearing anything, but now with social media we already knew what was going on.

"I felt the players were a little bit down before the game and I hope that we can recover as soon as possible, especially mentally because we have another challenge."

He added: "I know how tough this job is but I can't go home now thinking what is going to happen or isn't going to happen, I need to think about recovering the team as soon as possible.

"This Championship doesn't give you time to complain. It's just about keeping going and in two or three days we have the top-of-the-table team at home."

Forest will begin 2019 in 10th place after Tunnicliffe's stylish goal inside 10 minutes proved enough to give Millwall only their sixth win of the season – with all of them coming at The Den.

The visitors went close in the first half through a Joe Lolley volley before Matty Cash shot just wide, while Jack Colback also came close to an equaliser after the restart.

But Forest were unable to find a way past Lions keeper Jordan Archer and Millwall boss Neil Harris was pleased with his side's performance despite their failure to find a second goal.

"We knew it was going to be a close game, two different styles of play," he said. "Forest want to pass, pass, pass whereas we want to get the ball forward a little bit quicker and force the issue.

"Certainly, for the first 35, 40 minutes we completely dominated and were excellent. We pressed the ball, forced mistake after mistake.

"If we had just used the ball slightly better on the counter-attack we could have had more end product, but the same as Boxing Day, the goal was worthy of winning any game."

On the pressure on Karanka, Harris added: "It's modern-day football, short-termism, short memories. It's a big football club that craves Premier League football.

"They spent money in the summer. All us managers understand the pressure and the demands of the game. I think he's a smashing fellow and a good manager, so I'd like to see him given time."