Chelsea recovered from Antonio Rudiger's own goal to move up to fifth in the Premier League, as Thomas Tuchel's unbeaten start as manager continued with victory at Sheffield United.
The German, who took over from Frank Lampard last month, watched as his side struggled in the opening half hour on a freezing night as Oliver Burke fired wide in the opening minute.
But the visitors went ahead before the break when Mason Mount found the bottom corner following Timo Werner's cross from the left.
Chelsea then conceded the first goal of Tuchel's four-game reign in calamitous circumstances when Rudiger poked past Edouard Mendy into his own net.