Premier League referee Michael Oliver said he should have given more thought to Everton goalkeeper Jordan Pickford's wild tackle on Virgil van Dijk that left the Liverpool defender needing knee surgery instead of focusing on whether to award a penalty.
Pickford's reckless challenge, in a match between the Merseyside rivals in October, was made inside the penalty area but came after the referee had blown for offside.
The England goalkeeper was not cautioned for the tackle and retrospective action after the Football Association determined the incident was seen at the time by the match officials, including the video assistant referee (VAR).
"The thought initially was, 'it can't be a penalty because it's offside so we need to check the offside first'. I said to the VAR, 'if it's not offside I'm going to give a penalty'. I've watched it back so many times," Oliver told the Daily Mail.
"... We've all, myself included, not thought about the challenge as much as should have done. We could still have given offside and sent Pickford off.
"We got sucked too much into going step by step as opposed to thinking of the bigger process, which was considering the challenge as well and not just the fact it can't be a penalty."
League leaders Liverpool's three main centre backs -- Van Dijk, Joe Gomez and Joel Matip -- are all sidelined with injuries. They next face Manchester United in the league on Sunday.