West Ham United and Millwall have been warned about crowd trouble ahead of their Championship clash this weekend.
A number of measures have been taken in order to curb trouble, such as later pub opening times, increased police presence and asking players not to engage in over-the-top goal celebrations.
"We appreciate a healthy rivalry between the clubs but anything that deviates from this will be dealt with quickly and robustly," Chief Superintendent Sean Vickers said.
"There will be no excuses. If you are intent on trouble, you will be targeted by our officers and dealt with appropriately.
"I don't personally speak to the players but I will talk to the referee about the club rivalries and the players are told to manage their goal celebrations, so they do not cause any risk to anyone in the crowd."
The teams' last match at Upton Park three years ago resulted in clashes between fans, and one man was stabbed.
West Ham are currently top of the Championship, while Millwall are 21st.
