Greek tennis star Stefanos Tsitsipas said he was happy with how he responded after falling down by a set to Karen Khachanov in the Rome last-16. Khachanov won the opening set of the meeting versus Tsitsipas but the Greek dominated the rest of the match as he claimed a 4-6 6-0 6-3 victory. “It was a great, great match. I really upgraded my game in the second set,” Tsitsipas said. “I was really able to follow through after every shot. I loosened up a little bit and concentrated on depth a little bit more. “I hit great serves towards th …