Chido Obi is being discussed as a potential answer to Manchester United's goalscoring woes - but the 17-year-old is not in the squad for Thursday's Europa League last-16 first-leg tie against Real Sociedad.

United say the Danish forward is "ineligible for the competition" and cannot feature for the club this season in Europe.

But why?

Obi was signed from Arsenal's academy last October, aged 16.

After scoring a hat-trick in a 5-1 FA Youth Cup win over Chelsea on 12 February, he was drafted into United's first-team squad after they were hit by a number of injuries - including winger Amad Diallo - and a lack of forward options, with Marcus Rashford and Antony sent on loan in January.

Four days later he made his first senior appearance as a substitute in a 1-0 loss to Tottenham, becoming United's third-youngest ever Premier League player.

Obi's third appearance came on Sunday as United lost to Fulham on penalties in the FA Cup, replacing striker Rasmus Hojlund in the second half.

While £72m Denmark striker Hojlund and Netherlands international Joshua Zirkzee both managed one effort on goal, Obi had three and forced Fulham goalkeeper Bernd Leno into an outstanding reaction save.

United's hopes of a trophy this season and European football next season - vital for their financial issues - now rest on winning the Europa League.

Clubs were allowed to add three new players to the 'A' list of their 25-player European squad by the Uefa deadline on 6 February before the start of the knockout round.

United added January signings Patrick Dorgu and 18-year-old Ayden Heaven, specifically to boost Ruben Amorim's first-team squad.

But at that point Amorim was not considering Obi as a senior player and said the forward was someone who might get an opportunity later in the season.

In addition to increasing the 'A' list, clubs can add players to their 'B' list to play in Uefa competitions at any point up to 23:00 GMT the day before a game.

'B' list players are anyone who has been able to play for the club in question either for two continuous years from a player's 15th birthday or for two out of three years if the player has spent time at another club on loan.

Obi does not meet the criteria as he only joined United from Arsenal in October.

Other youngsters available for Thursday's game are Harry Amass, Louis Jackson, Habeeb Ogunneye, Jack Fletcher and Jayce Fitzgerald.

Premier League rules are different as they have an 'Under 21' list which is not included on the 25-man squad list.

Obi is one of 57 players who are named on this.