But another error by much-maligned keeper Kepa Arrizabalaga, who was involved in a mix-up with Kurt Zouma, gifted the visitors their second goal. Kai Havertz appeared to have spared his team-mates' blushes when the Germany midfielder restored Chelsea's lead.
Frank Lampard has confirmed that Edouard Mendy will play no part in Chelsea's Premier League clash with Southampton this weekend.
But, as ever with Chelsea, the miscues from Zouma and Kepa underlined problems that remain unsolved at the back and could prove fatal to their chances of mounting a title challenge. "We'll see a lot more of that from him".
Meanwhile, Brazilian center-back Silva has been banned from the game after having traveled a long way from South America and played against Peru in his nation's World Cup qualifiers on Wednesday. Ben Chilwell is fit to start at left-back.
Southampton have a striker with the clinical instincts to match Werner and Ings gave them a lifeline in the 43rd minute. The Frenchman lines-up alongside Jorginho so Mateo Kovacic misses out.
The 24-year-old German forward started in a more central role against the Saints and his opening goal was a brilliant individual finish that he scored after evading sliding defenders in the box, while his second was even more impressive as he lifted the ball over the onrushing goalkeeper and headed into the net. Christian Pulisic's incisive run and pass found Werner and he slipped the ball across to Havertz, who finished from 10 yards out.
As for Southampton, Theo Walcott makes his first start since re-joining the club on loan from Everton.