Second-half strikes from Jarrod Bowen, Emerson Palmieri and Michail Antonio helped a resurgent West Ham United beat FCSB.
The Irons' UEFA Europa Conference League Group B opener was preceded by a show of respect to Her Majesty Queen Elizabeth II, after the sad news of her passing broke before the fixture.
The Romanian visitors took the lead in the first half, through Andrei Cordea's close-ranged effort on 34 minutes.
Manager David Moyes rang the changes at half-time with Antonio, Lucas Paquetá and Bowen entering the fray.
It was Bowen who levelled the match from the penalty spot on 69 minutes, confidently dispatching his effort into the roof of the net after a foul on Maxwel Cornet.
Emerson put the Irons into the lead just a few minutes later, dispatching a low first-time effort under the FCSB shot-stopper after intense pressure from the home side.
Antonio wrapped up the three points with our third on 90 minutes, powering home a strike that Târnovanu could not keep out, despite getting a hand to the shot.
Check out the goals in the video player above!