Thomas Tuchel opted for major changes and gave a first start during his reign to Spanish goalkeeper Kepa Arrizabalaga as Chelsea overcame Barnsley 1-0 in the FA Cup.
There were 10 changes to the team, including starts for youngsters like Callum Hudson-Odoi and Billy Gilmour, as Chelsea beat the Championship side.
Their rivals made life difficult for the Blues, who had to wait until Reece James played in Tammy Abraham to score just after the hour mark.
It marked an improved second half after Chelsea had a slow start, with Abraham again proving to be the team's lucky charms.
With his goal at Oakwell, he has now scored six and assisted three in his last nine FA Cup appearances.