Matheus Cunha opened the scoring in the 27th minute from Patrick Dorgu's low cross. Before half-time, Bruno Fernandes finished a move involving Youri Tielemans, then Benjamin Sesko rounded the goalkeeper to establish a three-goal lead.
Sabah had threatened through a Joy-Lance Mickels header while the score was still 1-0, but did not take the opportunity. Making their first league-phase appearance, the Azerbaijani visitors struggled to contain United's combinations and quick attacks once the opening goal arrived.
Lisandro Martinez added the fourth in the 68th minute after a quickly taken free kick and a contribution from Joshua Zirkzee. Michael Carrick withdrew several regulars as attention turned towards Manchester City on September 13. The European opener provided three points, while the domestic meeting will offer a different test.