eased Ioannou away from a high ball and the former Celtic forward capitalised by sprinting past McCullough to tee up Piazon for a clinical finish into the roof of the net.
Only a fingertip save by Sutherland denied Feruz a goal of his own as the holders struggled to stay in the tie but the introduction of James Wilson, who has been troubled with a foot problem, brought fresh hope. However, Chelsea continued to carry the greater threat with Alex Kiwomya forcing another stop out of Sutherland. There was one final chance for Barmby but his left-foot drive crept agonisingly wide after being set up by Wilson.
United: Sutherland; Grimshaw, McCullough, Ioannou, Blackett; Rothwell, Pearson, Daehli (Rudge 83), van Velzen; Barmby; Byrne (Wilson 81). Subs not used: Coll, Hendrie, Ekangamene.