The Blues made a bright start to the match and worked a number of openings against their west London neighbours in the early exchanges, but they could not find a breakthrough and were sucker-punched in the second half.
Ethan Pinnock headed Brentford ahead from a corner after 58 minutes and as Chelsea committed men forward late on, Bryan Mbuemo wrapped up the victory deep into stoppage time after Robert Sanchez had gone up for a corner.
There were plenty of groans around Stamford Bridge – with the side having won just once at home in the Premier League this season – and Pochettino was seen exchanging words with one unhappy supporter just before half-time.
The fan had been yelling at Jackson while he was receiving instructions from his manager by the dugout during a break in play with Pochettino jumping to his striker – and the team’s – defence, though he downplayed the confrontation afterwards.
Asked what happened, Pochettino explained at his post-match press conference: ‘It was a moment that I think we all feel frustrated because after 40 minutes we’d played really well, created chances and we didn’t score.
‘In this moment it was a little bit down the energy inside the stadium.
‘And I’ll explain the situation, because it’s good to explain. He [Jackson] arrived to me and we were talking about his position on the pitch and to find some solutions and giving some directions to him.
‘And because it was really calm [quiet] in that moment, one fan said, “Oh wake up” and started to abuse a little bit, you know?
‘I don’t say abuse, but it’s abusing, and that for Nico meant he was losing a little bit of focus, and watching him I say, “Hey, Nico come on, be focused here”.
‘And repeat again, to stop [the fan] talking in this way, I said, “OK come on, support the players, we need support, stay behind the team”.
‘But that was it, nothing more. It was very respectful and the fan was very respectful. He said only “wake up” and the player took it in a bad way, it’s normal, no?
‘The player wanted to score, wanted to provide good things. But nothing more.’
Chelsea are next in action in the Carabao Cup on Wednesday night against Blackburn Rovers before travelling to north London to take on top-of-the-table Tottenham a week on Monday as Pochettino returns to his old stomping ground for the first time.
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