Former Arsenal midfielder Paul Merson believes Chelsea may need to sign a striker in the January transfer window.
The Blues spent £226.1 million on players to top the Premier League spending charts.
But big-money signings such as Kai Havertz and Timo Werner have failed to live up to their transfer fees thus far.
Having sat atop the Premier League last month, Frank Lampard's side are now down in ninth and have secured one win in five games.
The most recent of which came in a resounding 3-1 loss to Manchester City at the weekend.
With the winter window open this month, Merson believes there is still one crucial area that can be reinforced, and perhaps Chelsea director Marina Granovskaia should take note.
He told Sky Sports: "I don't know where Werner plays.
"I think Chelsea may have signed him to play as a striker, but that is not working, and if his best position is off the left, then Chelsea need a centre-forward.
"No disrespect to Olivier Giroud or Tammy Abraham, but you are not going to win the Premier League with those as your front two.
"Giroud and Abraham do great on their day, but they are not going to be in the top six Premier League goalscorers this season, or any season.
"How many teams have won the Premier League without having a player in the top six scorers?"
Lampard has been accused of not knowing his best starting lineup as he has rotated his side frequently this term.
But Merson said one part of the team picks itself.
"Chelsea are suffering from a major dip at the moment," he said. "Players are struggling, new signings are struggling, and four months into the season it appears that Frank Lampard does not know his best team..
"Frank has got to get a settled team. He knows his first-choice back five - Edouard Mendy, Reece James, Kurt Zouma, Thiago Silva, and Ben Chilwell - and that is solid.
"After that, it's bingo and it's clear he does not know his best midfield or front three.
"You would argue that N'Golo Kante and Mason Mount are next in the pecking order but that leaves Lampard needing to select four from eight internationals. Suddenly things start to mount up, and it's hard for him to pick the right team."
