BUCHAREST, Jan 30 (Reuters) - Manchester United ( MANU ) cruised through to the Europa League knockout stages after goals from Diogo Dalot and Kobbie Mainoo earned the Premier League side a 2-0 victory over Steaua Bucharest on Thursday.

Coming into their trip to Romania, United knew victory would guarantee them a top-eight finish in the league phase of the new-look Europa League, but the visitors struggled to create any openings of note in a poor first half.

The introduction of substitutes Alejandro Garnacho and Amad Diallo livened up Ruben Amorim's side in the second half, with Dalot tapping United in front on the hour mark.

Mainoo's smart finish eight minutes later killed off the hosts' chances of claiming a major scalp, helping United to finish third in the standings, while the defeat means Steaua must navigate a playoff to reach the last 16.