Manuel Pellegrini hopes Lucas Perez keeps on firing to help ease the potential loss of Marko Arnautovic, who hobbled off against Cardiff.
The former Arsenal striker made his mark from the bench as he scored twice in a 3-1 win - his first goals in the Premier League for almost two years.
Arnautovic was replaced by the Spaniard just before half-time after suffering a hamstring injury which will be assessed by the West Ham medical staff on Wednesday.
When asked about Perez's contribution was to the team, Pellegrini said: "It's very important for the team as we won the game. After that for different reasons as he hasn't started much before this game. The important thing is to have options. It's unfortunate for Arnautovic - I hope that he [Perez] continues."
Pellegrini was pleased with how his team responded to a flat period before the break where Joe Ralls let them off the hook by missing a penalty for Cardiff.
He admitted Perez's opening goal eased the tension and from that moment they never looked in trouble against a Cardiff side that collapsed in the second half.
Pellegrini added: "We improve a lot in the second half. It was a relief. The goal relieved the pressure. That's why we scored two more goals.
"Cardiff are a difficult team - they only lost 1-0 against Tottenham and Everton. They work very well in the style they like to play."