CAS announced Metalist had made "an urgent request for provisional measures...to obtain the temporary stay of the UEFA decision excluding the Ukrainian club from UEFA competitions...and its reinstatement in such competitions."
Metalist, due to face Schalke 04 in the two-legged Champions League playoff round later this month, were expelled by UEFA on Wednesday in connection with a domestic match-fixing case dating back to 2008.
Greek side PAOK Salonika, the team Metalist eliminated in the third qualifying round, have replaced them as Schalke's opponents.
CAS said it would ask UEFA and PAOK for written observations and would give more information on Friday evening.
Turkish side Fenerbahce, banned from European competition for two years over domestic match-fixing in 2011, have already been reinstated by CAS pending an appeal.
They play Arsenal in the two-legged playoff round with a final decision by CAS expected by August 28.
(Reporting by Brian Homewood; Editing by Tony Jimenez Reuters)
