Morata first started suffering problems with his back as early as mid-December.
Lionel Messi missed a penalty in that semi-final second leg and will be looking to redeem himself by settling an old score and putting Chelsea to the sword.
However, Barcelona have been incredible all season, so will prove a huge test for Chelsea, who overturned their recent poor results with an emphatic performance in the 3-0 win over bottom of the table West Brom.
"Chelsea is a big club, a club that has given me the opportunity to play as a starter, to grow even more", Morata told Movistar.
"It is essential to have fun at youth level, but I thought 'if I do not play 14-15 years for Atleti, I'm just not good enough'".
"That is until the physical problems arrived".
But the Spain global, who left for Chelsea in a £60m deal in the summer, admitted he need to leave for first-team football.
"I started at Atlético and it went very well", Morata said, "until at one point I started not to enjoy football so much, because I did not play much".
"I didn't play knockout games in the Champions League, neither against Barcelona, Atletico Madrid, Sevilla or Valencia. Life doesn't end when you leave Real Madrid, but I am still a fan of Real Madrid".