The England international has scored ten Premier League goals already this season, second only to Jamie Vardy, but was absent after picking up a hip injury in the Champions League draw with Valencia in midweek.
French World Cup winner Olivier Giroud was handed only his second league start of the season, but was part of a forward line that drew a blank, with Christian Pulisic particularly wasteful.
That meant that Aaron Creswell’s strike was enough to earn the visitors a much-needed three points, but Lampard insisted missing his first choice striker was not an excuse.
“It’s not down to one player,” Lampard said. “We didn’t have enough quality in the final third. My gripe this season is that we are not converting enough chances.
“Generally, collectively we could have handled that game better. This isn’t the worst thing for us as long as we react in the right way.”
Giroud’s inclusion was one of five changes to the side that had drawn 2-2 in the Mestalla on Wednesday night, but while several fringe players missed out on the chance to impress, Lampard defended his decision to rotate.
“Tammy was enforced,” he added. “At the same time I have to think about the squad and when we have a taxing game, I have to think about how fresh we are right now. We can’t get through the season with 10 or 11 players.”