Two goals in the second half secured a first home win of the season for Palace and Campbell believes the manager's team-talk was behind a much?improved display after the break.
"At half-time, I held my hands up because I was poor in the first half," said Campbell, who put Palace ahead six minutes into the second half before Mile Jedinak headed a second three minutes later.
"The manager said I needed to be more lively and get myself running about, so that is what I did in the second half. I put myself about a bit more and it helps the lads behind me if I am closing people down quicker. That really caused them problems.
"We knew it was going to be cagey because Leicester came off the back of a great win against Manchester United. But we came out second half and had a real go at them."
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