Chang masterclass aids Nishikori at Wimbledon
Kei Nishikori from Japan returns the ball during his match against Swiss Roger Federer at the ATP Gerry Weber Open tennis tournament in Halle, western Germany on June 14, 2014 - by Carmen Jaspersen
Nishikori arrives at the All England Club in good physical condition after recovering from the hip injury that forced him to withdraw from the Madrid Masters final against Rafael Nadal in May.
That injury was still troubling the world number 12 when he suffered a shock French Open first round defeat against Martin Klizan last month.
But Nishikori was able to recuperate for a week after his Paris exit before heading to the German grasscourt tournament in Halle, where he underwent intense practice sessions with American coach Chang, who has worked with the Japanese star since the start of the year, in a bid to improve his poor record on the surface.
The 24-year-old has never gone past the third round at Wimbledon in five attempts, but the difference after his work with former French Open champion Chang was clear to see as Nishikori reached the Halle semi-finals before losing to Roger Federer.
He is confident of maintaining that form at Wimbledon, where he faces France's Kenny De Schepper in the first round next week.
"I had two good weeks in Halle with Michael," Nishikori told reporters at Wimbledon on Saturday.
"We worked very hard on grass, that's something I've never done before.
"He was teaching me a lot of good stuff that I didn't know and hadn't done before. For sure he is helping my tennis grow.
"You can see my tennis is changing from last year. I am a little more aggressive.
"There are not many chances when you play the top guys so I am concentrating on looking for the ball that I can step into and attack."
Chang won't be joining Nishikori at Wimbledon -- they will link up again before the start of the American hard court season -- and that isn't ideal given the tricky transition from clay to grasscourts.
But Nishikori is sure his lessons with Chang and his strong recovery from injury will stand him in good stead.
"Physically I feel almost 100 percent perfect," he said. "I played three good matches in Halle and everything is good for next week. I'm very strong.
"At the French it was unfortunate because I was injured and couldn't practice beforehand.
"I was sad to lose in the first round, but coming here my body feels good.
"For me this is the toughest time to change from clay court to grass court. You have to change your tactics a little bit and also how you play; a shorter backswing and the return is different.
"The serve is very important here and I try to come to the net more."
De Schepper, a big-serving left-hander, could be a testing first opponent for Nishikori, who has never played the world number 67 before, but he is heading into the year's third Grand Slam brimming with belief.
"I feel more confidence now and even on grass I feel very confident," Nishikori said.