Roberto Firmino may lose his place in Liverpool's attacking trio with Juergen Klopp's side struggling for goals in recent weeks, former defender Jamie Carragher said.

Mohamed Salah, Sadio Mane and Firmino scored a combined 183 Premier League goals over the last four campaigns and helped the Merseyside club to their first title in 30 years last season.

But their form has dropped off recently and they have gone three league games without a goal, including Sunday's 0-0 draw with leaders Manchester United at Anfield.

While Carragher expects Salah and Mane's form to improve, he has expressed concerns about Firmino's long-term prospects.

"I'm still confident that Mane and Salah will start scoring goals again, but I must say I am worried for Firmino," Carragher told Sky Sports. "But he's there to chip in and when they're not scoring, and I just feel he needs to be a bigger goal threat."

Carragher said other aspects of Firmino's game have also seen a dipped this season.

"The counter-pressing and winning the ball back has dropped off with Firmino -- and not just this season," Carragher said.

"He's the one I'm worried about, whether it be a lack of form or maybe just that slow decline as you get a little bit older, which is natural for any attacker when they get to their late 20s."

Liverpool have gone four league games without a win and have dropped to fourth.