Lionel Messi will be sidelined from football activities for the next three weeks, due to a thigh injury he sustained against Atletico.
The Argentina international could no longer continue after a tussle with Diego Godin had him clutching his leg in pain.
The injury is a reoccurrence of one he sustained while on international duty. Messi will miss the UCL clash against Mochengladbach.
The 29-year-old will also be absent for clashes at Sporting Gijon and Celta Vigo, and is in a race against time to be fit for the visit of Manchester City to the Camp Nou in late October.
Barcelona’s woes were compounded against Atletico as Sergio Busquets also had to be substituted in the second half, though Andres Iniesta has confirmed it was only due to a fever.
Wednesday’s draw saw the Spanish champions fall three points behind leaders Real Madrid at the top of La Liga.