According to Goal, Lampard said that it was not a coincidence that Chelsea's recent slump in form came while Ziyech was unavailable for selection.
The Moroccan has not been able to play since he picked up a hamstring injury in Chelsea's 3-1 win over Leeds United earlier this month. But the Blues' coach said that Ziyech could make his return to the side in Chelsea's next game - against Manchester City on Sunday night.
However, that game going ahead itself is uncertain, after the COVID-19 outbreak in the Manchester City squad.
Since Ziyech's injury, Chelsea have picked up just four points from five Premier League games, and have lost to Wolverhampton Wanderers, Everton, and Arsenal in that period. The latest points dropped came against Aston Villa at Stamford Bridge on Monday night, as an Olivier Giroud opener was cancelled out by Anwar El Ghazi's equaliser.
"I think with Hakim, the way he was playing, he was being very effective for us in terms of assists, goal creation, chance creation and some goals," Lampard said.
"We were very fluid at the time. You're going to miss players at that level when they drop out and we want him back."
Frank Lampard praises Chelsea attitude in Aston Villa draw
Despite points being dropped in the game against Villa, Lampard was not entirely displeased by the performance.
"It's a draw against a good team. Our performance was good and we deserved to win. We've come through a difficult patch. We saw the attitude of the team today. The table is still tight and we remain close. Today I saw some good signs I like."
Young Englishman Callum Hudson-Odoi was also urged by Lampard to step up in terms of his end-product, despite good performances against Villa, and as a substitute against Arsenal before that.
"The obvious next part is end product," Lampard said.
"When you look around at the numbers that the top wingers produced in the Premier League in recent years, Callum definitely has the capabilities and that will be the next stage for him."
Lampard and the Blues now face a wait to learn whether their next game against Manchester City will take place at all.Published 29 Dec 2020, 17:18 IST