Gerrard has been rotating Buendia and Philippe Coutinho, rather than using both in the same starting line-up.
"You don't pick the team, do you?" Gerrard snapped at a reporter's questions about Buendia not starting.
"I do, so I make those decisions. We've got really good options in the final third. Emi Buendia will start matches for this team. He was winning the race for a starting spot in the opening game of the season.
"But he got a muscle injury in a behind-closed-doors friendly against Fulham and he missed close to a week. Then his training performance was slightly below what it had been prior to the injury so we have been patient with him.