Interim coach Sergi Barjuan saw Barca held to a 1-1 draw by Alaves in his first game in charge and his team was second best for long periods here.

But, amid talk of Barca being set to appoint club legend Xavi as Ronald Koeman's replacement, Sergi's team claimed a narrow win that means he can hand the reins to his successor with its position in Europe much healthier.

It was Fati's vicious close-range strike that made the difference in Kiev, the teenager rifling home in the 70th minute to send Barca second in Group E.

A promising start from Barca soon faded, with the visitor failing to produce a single shot on target in the first half.

It was only the wayward finishing of Mykola Shaparenko that prevented Barca from going into the interval behind, the midfielder twice shooting wide at the end of well-worked moves either side of Marc-Andre ter Stegen denying Carlos de Pena.

The same story played out in the early stages of the second half, with Barca struggling to create anything of note against a Dynamo defence that looked comfortable for much of the contest.

Fati looked to have won Barca a penalty in the 64th minute when he went down in the box, only for VAR to rule he had kicked his own leg, but he did then provide the crucial breakthrough by emphatically dispatching Oscar Mingueza's deflected cross.

Ter Stegen produced a fine diving save to prevent Viktor Tsygankov from equalising, Dynamo left waiting for its first goal of the campaign as Barca took a step towards the knockout stages.