Liverpool manager Rafael Benitez is hoping Steven Gerrard's injury-enforced absence does not derail the team's challenge for the title.
"He is an important player for us. It is always more difficult to play without him," said Benitez.
"You can't change things so it is better to concentrate on the next game.
"We have some problems with injuries and Portsmouth will be tough so we need players with fresh legs."
Gerrard's injury, in the 1-0 FA Cup fourth round replay defeat to Everton on Wednesday, is the latest in a number of distractions for a manager trying to win his club's first league title for 19 years.
"We are out of the cup so maybe we will have more time and the players will not play too many games so will be ready for the Champions League and Premier League," he said.
"We are in a very good position and we need to win against Portsmouth and keep going."
Forward Dirk Kuyt agreed with his manager: "We have lost one of our targets but we still have two more to go for because we are still in the Champions League and we are fighting for the Premier League title, so we cannot afford to be too downhearted," he said.
"The key now is how we react to this defeat. The positive thing from our point of view is that on the two other occasions we have lost games this season we managed to come back in the weeks that followed. That is what we must do now."