José Mourinho has admitted he is in the midst of “the worst period” of his managerial career as his Chelsea team continue to struggle for form both domestically and in Europe.

The reigning champions are seventh bottom in the Premier League, with eight points from seven matches, and face Southampton this weekend on the back of a dispiriting Champions League loss at Porto. There have been reports of unrest within the camp – denied by Mourinho – and the Chelsea boss acknowledges he has reached a low point in his managerial career.

“I define it as the worst period in my career with the worst results in my career,” he said.

“I get it as a fantastic experience – an experience that I don’t want to repeat. I want to finish it tomorrow and win some matches again. I think it comes too late [in my career]. To come after 15 years is too late, but it’s something that is helping me to be better. A great negative experience. It’s the worst period, the worst results. I’ve never lost so many matches. That’s a fact.

“But we [manager and squad] communicate openly. There are no prima donnas crying. Everyone wants to do well and accepts the criticisms, knows the job and knows what is letting the team down. Nobody wants to do that, but that’s the reality: for the second goal against Porto, Maicon should have been surrounded by three of our players, but they failed. They let the team down. But they know. We spoke about it because we try not to make mistakes, and when you make mistakes you have to speak about it.

“You know what I call that? In football? ‘Coaching’. Coaching. We speak about it. If it happens in the first half, we speak at half-time. If it happens in the second half, we speak the next day. Never after the game. Never. But in here we speak openly: ‘You did that’, ‘you could have done that’, ‘you could help your mate’, ‘I did that mistake but you could do a bit better to compensate for my mistake’. I don’t have prima donnas who cannot be criticised.”

Rumours over dissent within the camp circulated in the wake of Mourinho’s decision to travel to Porto with a squad lacking several key players: Oscar, Loïc Rémy and Radamel Falcao.

“I was told by my assistant, [the first-team fitness coach] Chris Jones, who stayed in London and didn’t travel that, on Tuesday, they worked fantastically well,” added Mourinho.

“That was the first reaction. They could have stayed here and not shown motivation but, because they knew they could be selected for the next match, they worked very hard and well on the Tuesday. It’s not easy to do that when the team is playing and you’re not with them, but they found that motivation. So fantastic. Then, in the last few days, normal business, working well. With me, everyone is working well.”

The Egyptian forward Mohamed Salah will complete a permanent move to Roma at the end of the season after the Italian club took up an option to make his loan move permanent for an undisclosed fee.