The Blues now face an uphill battle to reach the final of the Carabao Cup after Hayden Hackney’s first half goal gave the Championship side a narrow advantage ahead of the second leg at Stamford Bridge.
Chelsea missed a number of presentable chances, particularly in the first half, but looked sluggish after the interval and lacked the attacking flair that has characterised some of their recent performances.
After the final whistle, Thiago made his way over the Chelsea fans in order to apologise for a sub-par display but was met with a barrage of hostility.
Asked about the incident in his post-match press conference, Pochettino said: ‘Don’t be confused because the fans were reacting to Middlesbrough fans, not with our players, our fans were fantastic with us. I
‘I think it was Thiago and some players I listened, they were trying to calm our fans because I think it was a problem between the fans.
‘Not with our fans and players. Be careful how you translate to the media or our fans. Don’t confuse the people.’
The veteran centre-half, who is almost certain to leave Chelsea in the summer, took to Instagram later on Tuesday night to issue a message of defiance ahead of the return fixture.
He wrote: ‘I am the first one to feel frustration for today’s result. But there is still the second leg and we will give everything to reach the final.
‘We have to be together now more than ever. Thank you for being with us today!’
It is the second time in recent weeks that the experienced Brazilian has been the subject of the post-game narrative after he was caught looking disgusted with his teammates after they nearly threw away a three-goal lead at Luton.
‘Thiago is like this. He is always moaning and never happy – but that is good.
‘He is 39 years old and still playing. I think sometimes we are there on the pitch but sometimes it was the small details.
‘You want to show that you want to help the team and your emotion is there.’
‘It is amazing, 39 years old and still playing like a 20-year-old,’ Pochettino later told BBC Sport.
‘He brings his experience to the team and he is doing really well.’
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