Liverpool midfielder Javier Mascherano believes having Fernando Torres back in the starting XI gives the side a significant psychological advantage.
The Spain international, arguably one of the best strikers in the world, has been sorely missed in the last six weeks after being sidelined with a hernia problem.
However, the 25-year-old came off the bench against Wigan last night to score what turned out to be the winner on his 100th appearance for the club.
It was his first goal since October 31 and although he still has to sharpen up after a long lay-off, just having the Spaniard on the pitch against Wigan visibly lifted the team and the crowd.
"It is so important for us that Fernando stays fit," said Mascherano, who is also returning to his best after an inconsistent start to the season.
"We know that we can win games when he is not playing but, equally, when he is on the pitch, you can see the respect that other teams give him.
"He causes them so many problems. With Fernando and Stevie (Gerrard) on the pitch, we know that there is always a chance something special can happen.
"It is so good for our team and the confidence they give us.
"When they are not in the squad, others have to do their job and David Ngog has been doing his job really well."
The 20-year-old Frenchman is still learning what it takes to be Torres' deputy, but is showing signs of progression.
Ngog opened the scoring in the 10th minute with his sixth goal in 15 matches, of which only eight have been starts.
However, his statistics are dwarfed by those of Torres. His bundled effort against the Latics was his 61st goal for Liverpool in a century of appearances.
It was also his 49th goal in 69 Barclays Premier League matches and he is destined to go into the history books as the fastest Liverpool player to a half-century in the league.
His influence on the team is not lost on Mascherano, who just hopes the Spaniard can put his injury problems behind him now.
"Key players are the key players and you cannot change that. We need to keep the key players fit for the rest of the season," said the Argentina captain.
"We cannot forget that Stevie and Fernando have been coming back from injury and it is important to have them in the squad as they are important for us.
"We want to play better and improve, so it is important that we keep going.
"We will see if we can win at Portsmouth and if we can do that, it will be three amazing points.
"There has been a little bit of pressure but top players have that all the time."
There could have been more pressure on Liverpool had Wigan taken their chances at Anfield, especially substitute Jason Scotland, who volleyed against the crossbar from six yards when faced with an open goal.
However, Latics manager Roberto Martinez is backing the Trinidad and Tobago international, who has yet to score since his summer transfer from Coca-Cola Championship side Swansea.
"Jason is disappointed. He is a goalscorer and he wants goals but the way he works and the way he uses his link-up play has been exceptional this season so I am not too concerned about it," said the Spaniard.
"He knows when you score goals you get points for the team and Jason is making the transition really well in the Premier League.
"I'm sure it will be just a matter of time. Once he gets one, I'm sure that the rest will follow.
"Probably at the beginning [of the season] he was more focused on scoring goals but his contribution is more than just that.
"As long as he works the way he does I have no problem with him."
Wigan midfielder Mohamed Diame is a doubt for Monday's visit of Bolton after injuring medial knee ligaments at Anfield.