Slaven Bilic admitted it was a shame that West Ham's fine 2-1 win over rivals Chelsea was marred by more crowd trouble at London Stadium.
The Hammers secured a place in the quarter-finals of the EFL Cup with goals from Cheikhou Kouyate and Edimilson Fernandes before Gary Cahill's last-gasp consolation.
However, in the closing minutes, fighting broke out as stewards struggled to keep West Ham and Chelsea supporters apart, adding to disturbances in the club's previous matches against Watford and Middlesbrough.
Bilic insisted that his focus was on the victory, but added his disappointment at the incidents.
"It is [disappointing]," he told Sky Sports. "To be fair, I did notice it, but I was more concentrated telling [Aaron] Cresswell not to watch that and to be concentrated on the game.
"I don't know what happened. I saw something, but whatever happened, it's a shame because we should be talking only about this great football game and a great win."
The West Ham manager was, though, delighted with the way his players performed as they deservedly beat in-form Chelsea.
"You can have a plan and you always have a plan, but your opponents have a plan as well," Bilic said.
"As Mike Tyson said, you have a plan, then you get hit in the mouth and the whole plan is out. But we hit them in the mouth in the beginning of the game.
"They started good. Of course, they are Chelsea. But then we scored and after that, we played really fantastic and we should have been two up.
"The crucial moment was the beginning of the second half. When we scored, it lifted us and gave us extra strength.
"In the last half an hour, they pushed and put three world-class players on the pitch. It was hard to defend, but we defended great as a unit and we hurt them on the counter-attacks."
