[4][5] There he progressed through the club's youth academy and made his senior debut for the reserve side, Sevilla Atlético, on 12 June 2011 in a 3–1 home win over Guadalajara in the Segunda División B play-offs.

[7] Whilst playing for the reserve side, Moreno operated under the tutelage of Ramón Tejada who rotated him between attacking and defensive positions down the left-flank of the field.

[9][10] He ultimately made 17 appearances during a campaign blemished only by a straight red card he received following a confrontation with Gabi in a league match against Atlético Madrid.

[11][12] He enjoyed a breakthrough season in the 2013–14 campaign where he made 44 appearances in total for the club, including 14 in Sevilla's victorious run in the UEFA Europa League.

[19][20] He scored again in December, against Swansea City, but ultimately endured an inconsistent debut season at Anfield, with his attacking output not matched by his defensive performances.

However, on 20 September 2015, he made his first league start of the season, providing the assist for Danny Ings' first Liverpool goal in a 1–1 draw against Norwich City,[23] and was praised for his man of the match performance.

[24] His performance in the 2016 UEFA Europa League Final, where Liverpool lost 1–3 to his former club Sevilla, was heavily criticised by pundits and journalists for positioning and defensive errors.

[25][26][27][28][29][30] On 14 August 2016, Moreno started in the first game of the season, a 4–3 win at Arsenal, where he conceded a penalty and was criticised heavily for his performance, prompting a defence from his manager Jürgen Klopp.

[33] Moreno played more frequently at the start of the 2017–18 season,[34] but was criticised in November in a Champions League group game against Sevilla, in which Liverpool led 3–0 at half time but drew 3–3, and was defended by Klopp.