Jurgen Klopp described Sunderland as "the most defensive team I ever saw in my life" after his Liverpool side scrapped to a 2-0 win at Anfield.
Black Cats boss David Moyes said beforehand his team would "park the double-decker bus" on Saturday and they certainly adopted a defensive mindset, although it almost paid dividends as it took the home side 75 minutes to find a way through when Divock Origi curled home the opener.
James Milner added a late second from the penalty spot to send Liverpool to the top of the Premier League, ahead of Chelsea facing Tottenham later on Saturday.
Klopp said: "I was not in doubt about the result, I just tried to fix a few things like using space better. It was an intense game for us and a deserved win at the end.
"There is a lot to analyse. This was the most defensive team [Sunderland] I ever saw in my life.
"Sunderland always play a defensive style and that is okay. We forced them to be that. It is the most difficult thing in world football to come through but we stayed concentrated, worked for the moment and found a way."
Klopp cut a frustrated figure for most of the afternoon, prompting him to rouse the crowd with some frantic arm waving after 63 minutes.
The German added: "The excitement is in the detail and that means you have to celebrate before you score a goal and push the team on if possible. It worked out. It's important the crowd know about the importance of their support."
The only downside for Liverpool was a serious-looking injury for Philippe Coutinho, who was carried off on a stretcher after 30 minutes following an accidental collision with Didier Ndong.
"It is an ankle injury but we can't say anymore until we see a scan," said Klopp. "Roberto Firmino got a knock on the calf as well. That should not be that serious."