He argued that the condition of the field made it difficult for his players to play their natural game, even as Amakhosi claimed a hard-fought victory against opponents they had struggled to beat in the competition.
"The pitch made it tough for us to express ourselves," Youssef told the media.
"It wasn't ideal, but we worked hard to get the win."
ZESCO United coach Mathews Ndlovu was quick to dismiss the complaints, saying such comments were unnecessary at this stage of the tournament.
"At this stage, you are challenged at any pitch," Ndlovu said. "If that was their excuse, we won't complain when we travel to their stadium. Football is played on the pitch. We made a mistake, they capitalised - it's how you apply yourselves."
Both teams faced the same conditions during the match, and Ndlovu insisted the result came down to execution rather than the playing surface.
The sides will meet again on Sunday when ZESCO United travel to South Africa, hoping to avenge their defeat.
Kaizer Chiefs co-coach Khalil Ben Youssef has defended his side's pragmatic approach following their 1-0 CAF Confederation Cup Group D victory over ZESCO United at Levy Mwanawasa Stadium on Sunday.
CR Belouizdad moved to the top of CAF Confederation Cup Group C after a controlled 2-0 victory over Stellenbosch FC at the Nelson Mandela Stadium in Algiers on Sunday night.
Kaizer Chiefs defeated Zesco United 1-0 in their CAF Confederation Cup Group D encounter at Levy Mwanawasa Stadium in Uganda on Sunday.
ZESCO United have announced the signings of three new players, Opiyo Levis Omondi, Emmanuel Mwanza and Luka Mutoshi.
