In 2013, captain Sam Warburton was ruled out after picking up an injury in the second test while Dylan Hartley was replaced in the squad by Rory Best after picking up a 11-week suspension before the tour started.
Gatland said history could repeat itself and several players could still receive surprise call-ups.
"If you look at the history of the Lions, six to 10 players get replaced," Gatland said.
"That is what has happened on previous tours so there are six to 10 players out there who are probably going to be called upon at some stage on this tour.
"So be prepared and be ready if you get that opportunity to come out."
England flanker James Haskell, fullback Mike Brown and hooker Dylan Hartley were notable exclusions from Gatland's squad with Brown expressing his disappointment on Monday.
"I can understand the frustration and disappointment," Gatland said. "I am more than happy for him to give me a call if he feels he has been hard done by.
"There are a number of players in the same situation and if any player wants to call us we are more than happy to take that call.
"When we select a squad and make a decision on players it is not always about the rugby content."
The 10-match tour starts on June 3 and ends with back-to-back games against the All Blacks.
(Reporting by Aditi Prakash in Bengaluru; editing by Sudipto Ganguly)
Share
