Goalkeeper Mendy picked up an injury while on international duty with Senegal and Lampard must now decide whether to start Kepa Arrizabalaga or Willy Caballero in goal.
Silva is not injured but has been left out of the squad after making the mammoth round-trip to Peru for Brazil’s World Cup qualifier on Wednesday night.
However, there is some good news for Lampard as wingers Christian Pulisic and Hakim Ziyech are fit to return to the squad.
Pulisic has not started a game since going off injured in last season’s FA Cup final defeat to Arsenal, while Ziyech is yet to make his debut after arriving from Ajax in the summer.
Lampard added that the Moroccan will not ready to start but could make a cameo from the bench.
“I’m excited to see Hakim play,” said Lampard. “It feels like a long time since we brought him here, and he hasn’t played since the Dutch league finished before lockdown.”
Ben Chilwell is available for selection, despite withdrawing early from international duty with England.
The left-back missed England’s friendly against Wales because of a coronavirus breach and was released from the squad prior to Wednesday night’s 1-0 defeat to Denmark, in order to return to Cobham and build fitness ahead of the Saints clash.
Chelsea predicted XI: Kepa, James, Zouma, Christensen, Chilwell, Kante, Jorginho, Mount, Havertz, Pulisic, Werner