The 32-year-old striker has scored just two Premier League goals in 13 appearances this season and has struggled to hit top form for a side that have slumped to 18th position with 13 points in 15 matches.
But the former Tottenham forward has shown improvement in his last two top-flight outings, including scoring Fulham's second from the penalty spot in the 2-0 victory over Aston Villa last weekend.
And Riether feels Berbatov's talent is vital to the team.
Speaking to the club's official website, he said: "He's our best player, no doubt. We need him to get out of this situation and in the last couple of games he's been fantastic.
"He did some important runs for the defence as well. He worked hard and tried his best for the team. If we have a negative run, the famous players get picked out. But he showed he wants to have success with the team and he gave everything."
Fulham's performances over the last two fixtures will have impressed new head coach Rene Meulensteen, who replaced Martin Jol at Craven Cottage, with the 57-year-old paying the price for a run of five straight Premier League defeats.
Although Meulensteen's first game in charge ended in a 2-1 loss to Tottenham, the side bounced back against Villa and Riether has credited the Dutchman for galvanising the squad.
"He changed different things but it's important we as players react on the pitch," he continued. "We know we have fantastic players but we have to show it on the pitch. If you haven't got a team you'll win nothing.
"When he speaks to the team, it's very good and very motivating. You can see on the pitch that everyone is fighting for him."
Fulham will look for back-to-back victories when they visit Everton on Saturday, but history suggests it will be a tough ask for the London outfit, who have never won a league match at Goodison Park.
