The 22-year-old centre-back produced a towering display in Seville that saw him singled out for significant praise despite ending up on the losing side after the penalty shoot-out defeat to Eintracht Frankfurt.
His performance was branded "astonishing" by former Manchester United and Bayern Munich star Owen Hargreaves, who expects bigger clubs to take interest in the player on the back of his showing.
"My word, what a performance he put on," Hargreaves told BT Sport. “That was astonishing really, the energy and the effort that he had, the composure, everythng about his game was fantastic.
"I'm sure anybody watching him will be thinking, 'that's the type of player I need in my team'. To play that way with that effort and energy, asbolutely astonishing."
Bassey joined Rangers from Leicester City in the summer of 2020 after signing a pre-contract agreement.
McCoist branded the Nigerian international a "colossus" but warned that, with centre-back partner Connor Goldson set to depart the club under freedom of contract, Rangers must keep hold of Bassey for next season.
The Rangers icon said: "I thought Connor Goldson was excellent. His starting position for the goal could have been a yard deeper I thought Goldson played very well and it does look as though he is off so the last thing you want to be doing is losing your other centre-back who was a collosus tonight."