The Irons were thumped 5-1 at London stadium, which after conceding three goals in defeat at Sunderland last week leaves Potter under increasing pressure.
The West Ham manager said afterwards: "A tough evening for us, of course. Bitterly disappointed with the result. With the manner of the goals, we concede after starting the game well. Too cheap, I think against a top team, we have to say that, to concede the goals in the manner we have is an impossible task.
"As I said, goals change games. Goals affect things too much, and when they're cheap, like the ones we gave away, we have to do better. Until you can solve that, it's always difficult in the Premier League, especially against the top team. We have to improve a lot.
'When you concede the goals in the manner we have, it makes it difficult. The timing of them as well. We were sort of were a little bit unlucky with this, getting that offside goal, fine margins again, but nevertheless over the course of the game, you put yourself in a position where if you open up too much and press too much, you can get passed through.
"But at the same time we're at home and we need to create some pressure and try to get on the front foot and create some mistakes, so it was a tough evening for us."