Tammy Abraham scored his 12th goal of the season as Chelsea beat Barnsley 1-0 to reach the quarter-finals of the FA Cup.
Abraham tucked in his first goal of the Thomas Tuchel era in the second half and also headed off the line at the other end as the Blues knocked the Championship side out at Oakwell.
A young, fit Barnsley team gave a great account of themselves on a cold night in South Yorkshire, but it is Chelsea who will play Sheffield United in the last eight.
Chelsea have now won four and drawn one of their five games under Tuchel after he replaced Frank Lampard as head coach last month, and although they were not at their best, a much-changed Blues side had enough to edge through.
Callum Brittain missed a golden opportunity to put the Tykes in front 10 minutes in when he shot straight at Kepa Arrizabalaga from close range.
Chelsea should have had a penalty when Toby Sibbick caught Abraham before making contact with the ball, only for referee Martin Atkinson to wave play on.
Atkinson was right not to point to the spot following a tangle between Mads Andersen and Abraham, before Brittain's strike looked like it might be heading in, only to deflect wide off team-mate Victor Adeboyejo late in the first half.
Tuchel replaced Andreas Christensen, who took a knock on the head, and Marcos Alonso, bringing on Antonio Rudiger and Reece James after the break following a somewhat flat first-half display.
Barnsley showed more intensity than Chelsea as they pressed the Blues high up the field, although the visitors' Callum Hudson-Odoi flashed a shot wide after cutting in from the left at pace.
Rudiger then headed Hakim Ziyech's free-kick just wide after 63 minutes, but Abraham broke the deadlock when he tapped in a James cross a minute later, with the hosts feeling the flag should have gone up.
Home substitute Michael Sollbauer almost scored with his first touch, but alert Chelsea striker Abraham headed off the line as Barnsley were unable to force extra-time.