Former Liverpool defender Jamie Carragher has criticised Virgil van Dijk for his performance in the 2-1 defeat to Manchester United.
Goals from Jadon Sancho and Marcus Rashford helped United claim three points on Monday despite Mohamed Salah scoring late on.
Van Dijk faced criticism for failing to block Sancho's opener, and after the game, Carragher called the Dutchman's "intensity" into question.
Speaking to Sky Sports, Carragher said: "It's the only one thing I'd ever question van Dijk on as a player. If you're going through a checklist of a centre back, he's 10 out of 10 for most things.
"The one thing I do sometimes think is: does he lack a little bit of intensity at certain times?
"I know you never see him on the floor and that's a strength for a defender - if a defender's on the floor all the time, that's not a good sign.
"But now and again, when you're in the proverbial, you've got to throw yourself at (the ball). That one there (the Sancho goal) he was literally stood there. It's one where you've got to go flying out and just throw yourself at him.
"Slide along the floor, make yourself as big as possible. You can't just stand there. He almost made himself smaller, the way he stood.
"That's the one thing I sometimes think: go, be more aggressive, maybe slide in, throw yourself in front of something."
Van Dijk and his Liverpool teammates will look to bounce back from the defeat at Old Trafford when they play host to Bournemouth on Saturday.
