* Cilic pounded out 19 aces in quarter-final victory
* His 45 match wins this season second only to Federer (Adds quotes, detail, byline)
NEW YORK, Sept 4 A resurgent Marin Cilic blasted his way by sixth seed Tomas Berdych 6-2 6-4 7-6 (4) on Thursday to become the first Croatian to reach the U.S. Open semi-finals since his coach Goran Ivanisevic in 1996.
For Cilic, who missed last year's U.S. Open while serving a doping ban that cost him four months on the tour, the win ended an arduous wait to return to the last four of a grand slam for the first time since the 2010 Australian Open.
"I mean, it was a difficult period. I didn't know when I'm going to start back," said the 25-year-old Cilic. "But it was also a good period for me. I matured a bit more and I was working day after day.
"Of course it was a huge motivation for me when I came back. I felt that I was more happy. I was enjoying much more the tennis court and still working hard for it.
"I felt tougher with myself in preparations and during the matches just clearer with my goals."
Certainly since his return last October the 14th seed has been firing on all cylinders, winning events in Zagreb and Delray Beach while reaching the final in the Rotterdam.
His 45 match wins this season are second only to world number three Roger Federer (53) and his run to the Flushing Meadows semis has been workmanlike and included wins over 26th seed Gilles Simon and 18th seed Kevin Anderson.
"Even though I had great success beginning of the year, I felt that I started to play really well somewhere from French Open," said Cilic. "Since then I think the things are in good place for me and moving really, really good with everything."
Despite all the positives Cilic claims to have gained from his brief exile from the sport he remains unhappy that he was found guilty of taking a tainted supplement given to him by his mother.
"It angered me how all the process went because it was not fair to me," said Cilic, who maintains he never knowingly took any performance-enhancing drugs. "It wouldn't be fair to any tennis player.
"So that was just very bad memories. But, you know, when you're against big organisations you are small ants. You can't do much. So I just accepted it.
"When I came back to the tennis court I erased it from my memory. I just used the positive parts."
Certainly there were plenty of positives to be found in Cilic's quarter-final performance.
Cilic, who pounded out 19 aces, had his Czech opponent under pressure right from the start breaking Berdych at the first opportunity in the first two sets to grab a 2-0 lead.
Berdych turned the tables on the 14th-seeded Croatian in the third and raced out to a 3-0 lead but Cilic, relying on his booming serve, broke back and forced a tiebreak before clinching the match with a thundering ace and forehand winner on the final two points.
"I start pretty terribly. It was not the way to start the match like that," said Berdych. "Then it obviously was really tough to catch up."
Up next for Cilic is the winner between five-times U.S. Open champion Federer and Frenchman Gael Monfils, who play later on Thursday. (Editing by Frank Pingue)