West Ham manager Slaven Bilic was "embarrassed" by his side's first-half display in the 4-2 defeat to West Brom and concedes there are issues within his squad that need addressing.
Bilic's men dominated possession and territory in Saturday's Premier League clash at The Hawthorns, but found themselves 3-0 down by half-time - Nacer Chadli's penalty and strikes from Salomon Rondon and James McClean doing the damage for the hosts.
The visitors, who found themselves further behind when Chadli doubled his tally 10 minutes after the restart, did manage to haul themselves back into proceedings with a header from Michail Antonio and a Manuel Lanzini penalty, but could do nothing more as they slumped to a second successive 4-2 loss.
And Bilic did not hold back in his frank assessment West Ham's display.
"West Brom deserved it. I felt embarrassed at half-time. We were three down and we can say that some of the goals were individual mistakes," Bilic said.
"We have a problem, starting with me. I know that we have a problem and I am the manager and I have to do everything to turn this around, solve that problem.
"This is the second week in a row we are forgetting the basics. We have to do something. I know what my team is capable of.
"It's as difficult spell as I've had since taking over. At half-time, I asked for a reaction and we got that after changes.
"West Brom showed their character after half-time, we played good football in the second half but I hate to say again, the words I said against Watford, that if you continue to defend like this as a team you can't win a Premier League game.
"There were some positive things in the second half, but we want action not reaction."