The Spanish centre-forward has not featured in Antonio Conte's squad lists since mid-January and this week, the Blues manager announced that the player is carrying a back injury.
However, a chipped goal by Ramires put Chelsea ahead on away goals before Fernando Torres sealed Barca's elimination in stoppage time.
But he has struggled since, scoring just two in his last 10 league games and attracting criticism for several wasteful performances in front of goal.
Interestingly, although it is only February, Morata has already played more minutes for Chelsea this campaign than he has ever played for any of his former club's during an entire season.
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.
"That is until the physical problems arrived". I wanted to play at Atlético, but I did not have fun. "I wasn't okay to play".
'I played lots in my home, with my team, with my friends, ' he added. "We won the league and Champions League".
"He called me after a bad training session and said to me that if you start well (in your career) then you will never have to work again in your life... but right now you have to decide where you want to go, so work well".
'But I didn't play knockout games in the Champions League, neither against Barcelona, Atletico Madrd, Sevilla or Valencia.