The Blues have played 11 games at Wembley since the national stadium reopened in 2007 and Lamps has started every time.
Lampard admitted: "Things change.
"Automatic selection depends on how you're playing, what manager you have and your relationship with him.
"I don't think anyone is an automatic selection with the manager at the moment as there are a lot of games and he's changing his team regularly. I've been lucky enough to have had a lot of success at Wembley with England and Chelsea.
"But I'm not sure if I'm playing against City on Sunday. No one is."