The Blues took an early lead once Batshuayi’s strike deflected off Hull’s Ryan Tafazolli and therefore the ball flew on the far side wrong-footed goalkeeper George Long.
Chelsea dominated the remainder of the half with Long to form to make a series of fine saves, however once the break the Championship side enjoyed a spell of domination where they threatened an equaliser.
Herbie Kane did not build the foremost of a free-kick whereas Jarrod Bowen had the Chelsea defence scrambling with a piercing run however place his shot simply over the bar.
The hosts’ hopes were knocked, though, once Chelsea added a second from a free-kick as Tomori, who had a season-long loan at Hull 2 years agone, nodded in Ross Barkley’s delivery for his second goal for Frank Lampard’s side.
Chelsea double went near to adding a 3rd through Pedro, who 1st placed an attempt simply wide of the way post before clipping an attempt over the goalkeeper just for the ball to land within the side-netting.
Instead it absolutely was Hull who scored to line up a tense finale as Kamil Grosicki’s free-kick from the edge of the box took a wicked deflection to land within the back of the net.
However, Chelsea prevailed to edge triumph and guarantee their place in Monday’s fifth-round draw.