Chelsea manager Frank Lampard conceded Timo Werner didn't offer his side enough with or without the ball during a 3-1 loss against Arsenal on Saturday.
Werner, who has now gone 10 games without a goal in all competitions for the Blues, was replaced at half-time by Callum Hudson-Odoi with Lampard's side trailing 2-0.
The change would fail to turn the tide however with Bukayo Saka adding the Gunners' third in the 56th minute before Tammy Abraham bagged a consolation goal five minutes before full-time.
Currently experiencing his longest goal drought at club level since 2016, Werner is seemingly struggling after an encouraging start to life at Stamford Bridge with Lampard desperate to get more out of the German international.
"Certainly the goals not going in is always something an attacking player will get judged on," Lampard said when asked about Werner in his post-match press conference.
"The subs, I could have made more. But I felt I had to make the subs in those two areas to inject energy.
"For today, TImo wasn't giving us enough with or without the ball. Some of it we have to give him time. I keep saying the same thing because it's a different league but we also have to get there quickly.
"We'll see about the tiredness - I'll have a conversation with him. But I felt I had to make changes to change the course of the match."
Something else Lampard will have to give some thought to over the coming days is who will take the Blues' spot-kicks moving forward with Jorginho having his injury-time effort saved at the Emirates.
The Italian midfielder had netted his first eight penalties for Chelsea but has now failed to convert three of his past six with Werner and Abraham waiting in the wings to step up if called upon.
"We'll see. I won't comment on that one at the minute. Jorginho's performance, he added a lot to the team in the second half so we'll deal with the penalties going forward," Lampard said.
Chelsea have a short turnaround before facing high-flying Aston Villa at home on Monday with Dean Smith's side currently one place ahead of Lampard's men in sixth and with two games in hand.