Chelsea must improve defensively to "compete with the big boys", according to Jimmy Floyd Hasselbaink, who suggests the Blues are in desperate need of fresh blood at the back.
Frank Lampard is on the verge of achieving a highly commendable first season in charge at Stamford Bridge.
Chelsea are sitting third in the Premier League with only two fixtures left to play after beating Norwich City 1-0 last time out, and they have an FA Cup semi-final date against Manchester United to look forward to this weekend.
The Blues also still have an outside chance of progressing in the Champions League, with Lampard's side 3-0 down from the first leg of their last-16 tie with Bayern Munich.
Lampard has been able to steer the team in the right direction despite being hampered with a transfer ban last summer, which allowed him to bring through a number of promising academy stars.
The likes of Mason Mount, Tammy Abraham, Reece James and Fikayo Tomori have all shone on an individual level, but Chelsea have looked vulnerable in defence throughout the campaign.
The Blues have shipped 49 Premier League goals in total, more than any other club in the top 10, and Hasselbaink says changes will be necessary for his old club to start challenging the elite again.
"If you look at the team Frank has, with what he has got, he’s done brilliant," The former Chelsea striker told Premier League Productions. "If you analyse them very, very well they are in the top four but they have had 49 goals against them – that is way too much.
"If you want to compete with the big boys that [defensive record] has to get better significantly.
"If you asked him (Lampard), that’s the department that he is really disappointed about. If you see the type of goals that are going in they are easy to defend.
"They’re goals that you should defend if you are in the top four or if you are going for the league, those type of goals you should know how to easily deal with."
Hakim Ziyech and Timo Werner have already been snapped up ahead of the summer transfer window, but Hasselbaink has stressed the need for further reinforcements to help aid the development of the younger members of the squad.
He added: "I think they have to improve the squad. Last year they couldn’t get new talent in which has helped the younger ones but to make the younger ones better you have to improve the squad with really good players, players who are better [than those that are already there]."