Sam Allardyce believes that Jamie Vardy's killer instinct was the difference as Leicester City sealed a 2-0 win over Sunderland on Sunday.
The England international raced onto a long ball from Danny Drinkwater to put the Premier League leaders ahead before he netted a second in injury time with a fine solo run and finish.
Allardyce felt there was little to choose between the teams in a tense encounter at the Stadium of Light, but felt Vardy's clinical touch - and his own side's poor response to the opening goal - proved pivotal.
"We didn't pass it anywhere near as good as we can and I think that was our main problem, not Leicester," he told Sky Sports.
"I can't see them shutting us down better than any other team but our passing game was nowhere near as good as it was against West Brom.
"Our defence allows Jamie Vardy to do what we said was his main strength. Unfortunately we weren't ready for it, and he does what every top striker does and why Leicester are top of the league - he scores it. That was the difference.
"The disappointing thing was how we reacted to that, we were very poor after they scored. Apart from the one chance - Jack Rodwell should have scored. I'm really disappointed at allowing Leicester in as easily as we did, particularly for the first goal.
"Leicester weren't better than us but they're better at digging out a result. That's why they are where they are."
Allardyce feels that a failure to secure victories against West Brom and Newcastle United in recent weeks led to jitters among his players which made the game much more difficult.
"We were more nervous than I've seen us before and it's a legacy of not picking up the points when we should have done," he said. "The extra pressure caused us to do the wrong things in the last 10 or 15 minutes to get back in the game."
Sunderland remain four points from safety and face Norwich City - who sit directly above them in the table - next week.