The 28-year-old playmaker pulled out with an Achilles tendon strain while Modric has been ruled out for a month after undergoing knee surgery last week.
"Modric, Rakitic and Lovren are all out of the upcoming qualifiers but I have a pretty clear idea who will replace them in the starting line-up," Cacic told a news conference.
"The Achilles tendon strain forced Rakitic to miss Barcelona's 4-3 defeat at Celta Vigo on Sunday while Lovren has a groin injury, but neither of them require surgery."
The Croatians, held to a 1-1 home draw by Turkey in their opening Group I match, are away to Kosovo on Thursday and visit the Finns on Sunday.
Cacic acknowledged that only two wins would do despite Croatia's woes, compounded by several regular starters being down the pecking order at their clubs.
"Some things are out of my hands but there will be no excuse if we don't win both games because we are a better-ranked team than both Kosovo and Finland," said the 63-year-old coach.
"The most important thing is that all our strikers are fit."
(Writing by Zoran Milosavljevic in Belgrade; Editing by Ed Osmond)
