World number three Roger Federer survived two match points to advance past Croatian Borna Coric into the Italian Open quarter-finals.
After rain wiped out play on Wednesday, Federer played two matches on Thursday.
He came through 2-6, 6-4, 7-6 (9/7) against 13th seed Comic after earlier beating Portugal’s Joao Sousa 6-4, 6-3 in the second round.
Federer will next face eighth-seed Stefanos Tsitsipas, who defeated Italian Fabio Fognini 6-4, 6-3 in an hour and 12 minutes.