- Hamilton: Chelsea, Lampard are running short on time
Ziyech went off with a hamstring injury during Chelsea's win over Leeds United on Dec. 5 and the Blues have won only one of their five league games since then, losing three and drawing 1-1 on Monday with Aston Villa.
"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."
Lampard said he was hopeful that Ziyech might feature on Sunday if the game goes ahead -- Manchester City's game against Everton on Monday was called off due to new COVID-19 cases reported at City.
The Blues coach praised the passing of Callum Hudson-Odoi, another Chelsea winger, who made a rare start for the Blues on Monday after impressing as a second-half substitute in an otherwise dismal 3-1 defeat to Arsenal on Saturday.
"The obvious next part is end product," Lampard said, urging Hudson-Odoi to step up in terms of assists and scoring.
"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," he said.
Monday's result was the second straight start in which Christian Pulisic went the full match. The United States star had been bothererd by injuries at the start of the season which forced him to miss significant time.
"Christian was really bright all game. That's great for him, fitness-wise, to play two games in such a short space of time," Pulisic said. "He created plenty of chances, he had an opportunity himself when he hit the side-netting and it looked like it was in but overall, he was really bright."