Liverpool boss Jurgen Klopp says their defensive display against Brentford is "not a concern" going into the Champions League group game with Porto.
The Reds' 3-3 draw on Saturday was the first time they conceded three in a match since the European defeat by Real Madrid in April.
"We didn't defend at our highest level so we have to improve," said Klopp.
"We don't make these things bigger than they are but you have to show a reaction."
Liverpool came from behind to secure a 3-2 victory in their Group B opener against AC Milan after going 2-1 down before Mohamed Salah's equaliser and Jordan Henderson's 69th-minute winner.