Sanz, who was unveiled as Slavisa Jokanovic’s assistant when the former Watford and Fulham manager officially took charge in July, worked alongside the Catalans director of football Mateu Alemany at Valencia before moving to England.
Alemany moved to the Nou Camp following Joan Laporta’s re-election as president and oversaw the investigation into why Collado’s proposed loan switch to Bramall Lane collapsed ahead of the August deadline.
Despite frustrating the La Liga giants by deciding to pull-out of an arrangement which had been agreed in principle, United will hope Sanz’s relationship with Alemany can smooth out any potential issues if Jokanovic asks them to return to the negotiating table.
The pair also boast spells at RCD Mallorca on their respective CV’s, although their paths did not cross at San Moix.
Jokanovic, who also counts Barcelona’s international technical advisor Jordi Cruyff as a friend, identified Collado as a possible signing soon after being appointed as Chris Wilder’s successor in July. With neither of the two wingers he wanted to recruit materialising during the previous window, the 53-year-old has requested those vacancies are filled when the market reopens in January.
Collado, aged 22, has made two senior appearances for Barcelona after progressing through their youth system and was a member of the team which beat Chelsea in the 2018 UEFA Youth League final.
He started his career with CE Mercantil before entering the famous La Masia academy following an impressive spell with neighbours Espanyol.
Collado, who can perform a variety of attacking roles, has also been capped by Spain at under-19 level and is a former captain of Barcelona B; scoring 18 goals in 83 appearances for the Segunda B outfit.
He made his debut for the five time European champions against Celta Vigo in May 2019, under the tutelage of Ernesto Valverde.