Diego Costa admits it was a mistake to throw a bib at Jose Mourinho and insists his...

Diego Costa admits it was a mistake to throw a bib at Jose Mourinho and insists his relationship with the Chelsea manager is 'amazing'.

The Spain striker tossed the training garment over his shoulder as he came back into the dug-out during the 0-0 draw at Tottenham on November 29.

Although it missed Mourinho, the Chelsea manager was asked about the incident afterwards and played it down as he insisted Costa's behaviour was normal.

The player himself has conceded he should not have done it, while pledging to improve having struggled for much of 2015.

"The bib [incident] is in the past," he told Spanish radio station Onda Cero after Chelsea qualified for the knockout phase of the Champions League with a 2-0 defeat of Porto.

"I made a mistake but my relationship with Mourinho is amazing, we get on really well. There are things you need to control, but the bib thing was an impulse.

"The truth is Chelsea haven't been in a great moment, above all losing the other day at home. Today it was important to win to make the fans happy and to recover our confidence."

After scoring 18 goals up to mid-January, Costa has only found the net another seven times since with just four this term.

Having come off the bench during the 1-0 weekend defeat to Bournemouth, he was restored to the starting line-up against Porto and forced the opening goal as his attempt deflected in off Ivan Marcano, before Willian clinched victory in the second half.

He wants to build on that with club and country, adding: "I have to improve a bit. The start of the season has not been good for me, not in how I have played nor in goals.

"I know I have to be better to go to Euro 2016 with Spain. I have to work hard and fight but I know I have time to improve and I hope I will."