In a battle pitting a pair of 1.98-metre (6-feet-6 inches) players with big serves and ground strokes, Zverev's superior return game was the difference on Saturday, reports Efe.
Even so, Cilic, the World No. 5, had five set points in the marathon first-set tiebreaker and also went up an early service break in the second set.
The third-ranked German showcased his strong service game and rock solid ground strokes, and his fiery temper and competitive spirit were also on display at the Foro Italico.
In the tie-breaker, Zverev drew whistles from the crowd when he broke his racquet after losing an important point.
Seemingly annoyed by the rowdy fans but also spurred on by their energy, Zverev went on to win that set and then made a gesture to the crowd indicating he can give as well as he can take.
Despite losing his serve early in the second set, Zverev dominated the latter stage of the match to clinch his 13th consecutive victory, all of them coming on clay.
"It was very tough. It's always tough playing Marin. He's one of the best players on Tour right now," the 21-year-old Zverev was quoted as saying afterward on the ATP World Tour's Web site.
"He knows what it takes to win the big matches in the big moments so I had to play my best to get the win today."
Next up for the German in Sunday's final will be Spanish World No. 2 and seven-time champion Rafael Nadal, who held off a stern challenge from a resurgent Novak Djokovic in a 7-6 (7-4), 6-3 semi-final victory earlier Saturday.
Zverev will try to perform better than he did in a lopsided 6-1, 6-4, 6-4 loss to the Spaniard in a Davis Cup match on clay in April.
The 31-year-old Nadal can extend his record haul of Italian Open titles to eight and also regain the top spot in the ATP rankings from Swiss great Roger Federer with a win on Sunday.
Nadal, Djokovic and Zverev will all be contenders at tennis' biggest clay-court event, the French Open, which gets under way on May 27.
The 36-year-old Federer, who has opted to skip the entire clay-court season for the second straight year to avoid wear-and-tear on his body, will not play at Roland Garros for the third consecutive time.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
