Ryan Gravenberch benefited from an error by Union Saint-Gilloise goalkeeper Anthony Moris to score his first goal for the club as Liverpool laboured to a 2-0 Europa League victory to maintain their 100 per cent record in Group E.For all the attacking firepower at their disposal - and it was considerable with Mohamed Salah, Darwin Nunez and Diogo Jota boasting 248 goals between them - it was a 21-year-old former Ajax and Bayern Munich midfielder who had scored just nine in five years who popped up with the breakthrough at a crucial moment a minute before half-time.That two of the front three were replaced at the interval was more down to a prepared plan rather than a reflection of their first-half contributions but if either had been anywhere close to their sharpest the game would have been out of sight before Gravenberch's intervention.Jota remained on for the whole game and scored the second with a breakaway in added time to ease any late nerves.Salah's first Europa League start for the club would have led to speculation about just how much devastation he could inflict, especially after his 16-minute cameo in their first European game produced a goal, an assist and a couple of other chances.In his 150th game at Anfield he should have added to the 103 he has scored already on this ground as early as the fifth minute.The excellent young centre-back Jarrell Quansah, deputising for rested captain Virgil van Dijk, won the ball high in midfield and released the Egypt international through the middle but he could not beat the goalkeeper.It was the beginning of a long list of chances ultimately concluded by Gravenberch's close-range effort and while Liverpool never looked in any real danger after Gustaf Nilsson had headed over