Liverpool should have taken more risks with their substitutions against Manchester United, says Jamie Carragher.
Liverpool fought tirelessly for the victory, registering 18 shots to United's six, but a dogged defensive display, coupled with the brilliance of David de Gea kept the hosts at bay.
The home team dominated possession and territory, especially in the second half as United failed to register a shot on goal after the break.
Klopp freshened up his team during the latter stages by bringing on Daniel Sturridge, Alex Oxlade-Chamberlain and Dominic Solanke for his front three of Philippe Coutinho, Mohamed Salah and Roberto Firmino.
Carragher questioned Klopp's decision not to remove one of the midfield three instead, in order to put more pressure on the United backline.
"Jurgen Klopp made changes but he still kept the three-man midfield the same," he said.
"Manchester United showed such a lack of ambition it was worth taking a risk by leaving Coutinho on and bringing on another attacking player. Yes, you can get done on the counter but it was obvious United were here for a 0-0 and hoping to nick a goal from a set-piece or a counter-attack. I think Liverpool should have taken the risk to take (Georginio) Wijnaldum or (Emre) Can off.
"It's not easy as a manager but I'd have taken that chance earlier and the substitutions shouldn't have been just player for player, but more tactical.
"It would have given Liverpool an extra attacking player on the pitch - it could have cost them the game, but it could have won them the game - but the position Liverpool are in, it was a game they had to go for."
Liverpool, who have not tasted victory over their fierce rivals in the Premier League since March 2014, failed to cut the gap on United, who remain seven points clear of them after stretching their unbeaten run to eight games.
Meanwhile, Klopp's men have won just one of their last five Premier League matches and Carragher thinks they can forget about challenging for outright honours in the league this season.
"Liverpool will be looking around the clubs going for top-four and how far they are behind those positions," he said.
"Even at the start of the season I don't think Liverpool fans expected them to win the title - I certainly didn't.
"Liverpool will be more interested in Arsenal's results - maybe Chelsea and Tottenham - although those two probably think they're capable of catching the two Manchester clubs."