"The thing he has to improve even more is his performance in Masters 1000. He’s very poor,” Ivanisevic was quoted as saying by the Desert Sun. “Lots of points there. It’s better to play good one 1000 than five of these 250s."
Cilic has not made it past the second round of a Masters event since reaching the round of 16 in Monte Carlo last April.
But Ivanisevic thinks after winning 14 of his last 15 matches, including victories over Jo-Wilfried Tsonga and Andy Murray in Rotterdam, Cilic could be ready for a big performance at a big tournament.
"He needs to believe. I think he believes now and he’s capable of beating anyone," said Ivanisevic.
Cilic's most-noted improvement has been on serve, which was Ivanisevic's biggest strength. The two began working together towards the end of last year, when Cilic returned to the tour after his suspension for testing positive for a banned stimulant was reduced by the Court of Arbitration for Sport.
Cilic is serving a career-high 11.2 aces per match and winning 81 percent of his service games this season.
"For him, he’s a tall guy, he needed to be more aggressive,” Ivanisevic said. “So he worked on the serve, he worked on the first shot to be more aggressive, try to come in. Not try to finish the ball at the net necessarily, but still look for the opportunity to come to the net.”