The Shenzhen Challenger runs 21-27 April.Veteran tennis writer Robert Davis will be following the ATP Challenger Tour circuit this year and will write a series of reports. This week, he is at the ATP Challenger Tour event in Shenzhen, China.

The heat is fast rising in ATP Challenger Tour Supervisor Ed Hardisty’s office at the Gemdale Tennis Center in Shenzhen, China.

Tension is in the air as players are swarming all around Hardisty’s desk studying the doubles sign-in sheet, crossing out old and scribbling in new names with haste. There are only a few minutes left before the sign-in closes and the cut-off number creeps lower and lower. For more than a few teams it is not looking good. They start swapping partners and cutting deals.

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Some players that confidently expected to be in the main draw have yet to arrive, like Thailand’s Danai Udomchoke who was aloft somewhere between Bangkok and Shenzhen. Little does Udomchoke know that he has been switched and is now partnered with Yuichi Sugita of Japan.

Players on the cusp scramble to get in the draw and finally, Hardisty bangs on his desk, indicating that time is up. Last in: Go Soeda and Yasutaka Uchiyama, whose combined position in the Emirates ATP Rankings is 332.

Players excluded from the tournament left Hardisty’s office shaking their heads and cursing their luck. A cut-off this low is a rare event on the Challenger circuit but it is a sign of the times: ATP Challengers are getting tougher to enter each week as more higher ranked players participate.

Here in Shenzhen there have not been many, if any, days with sunny skies and fluffy white clouds since we arrived. I have not heard any players complaining, though, as they choose to see the bright side of the dreary weather – at least it is neither hot nor humid.

At the Gemdale Tennis Center, construction sites with tall buildings, heavy machinery and towering cranes surround us. China seems to have embraced a ‘big and bigger’ mantra – at least with the new tennis centres erected here. Though Shenzhen has been called the nation’s industrial capital, it is also fast becoming its headquarters for tennis.

In Shenzhen there are two major tennis centres that boast 16 outdoor courts or more. In addition to this week’s ATP Challenger event, there is the ATP World Tour Shenzhen Open, debuting this year. The WTA Tour has an event here. Former World No. 1 Juan Carlos Ferrero is opening a tennis academy at the Gemdale Tennis Club.

I mentioned that the ATP Challenger Tour is getting tougher and as evidence just look at Shenzhen’s No. 1 seed, Yen-Hsun Lu. The Taiwanese player is No. 49 in the Emirates ATP Rankings, and this season he has made finals of Auckland (l. to Isner), the semi-finals at Memphis (l. to Karlovic), the third round of Indian Wells (l. to Isner) and second round of Monte-Carlo (l. to Raonic).

In the locker room, Lu is known and respected as the constant professional. Throughout his entire career, Lu has left no stone unturned. On-site you do not have to look hard to find ‘Rendy’. If he is not on the court, then you can find him on the training table getting taped or stretched, or in the gym. Lu’s work ethic is the kind that other coaches point to when they are teaching young players what it takes to be successful on tour.

In addition to holding the ATP Challenger Tour record for most titles (20), Lu also compiled some major wins, upsetting Andy Roddick on Centre Court at Wimbledon (2010) in a quarter-final run, and defeating four-time Auckland champion David Ferrer this year for a berth in the final.

When asked what was he doing here when only last week he participated in the Monte-Carlo Rolex Masters main draw, he replied in his typical humble manner.

“I want to do well in my home town tournament (Taipei) next week and I thought that this tournament would be good preparation,” explained Lu. “Of course, I feel the pressure being the top seed, but it is no different than the top players on the ATP World Tour feel when they play [250-level events].

“When you are the top seed, everybody expects you to win the tournament and you have higher expectations. The Challenger Tour has some very good players and I know that I can lose in the first round if I am not one hundred per cent prepared and play my best.

“I have a lot of respect for the Challengers and the players here and I try to approach each day just like I do on the ATP World Tour.”

If Lu is using Challenger tournaments to keep his skills sharp for the ATP World Tour, then Australian Samuel Groth is using the Challengers as a stepping stone to that main stage.

Shenzhen GrothJust a few weeks ago, Groth won his first Challenger title in Rimouski (d. Pavic). A big mountain of a man at 6’4” and 205 pounds, and looking more like he belongs in the cast of ‘Spartacus’ than on tour, Groth does not play finesse tennis. Instead you can file him in the big-banger, shock-and-awe category. Just a couple of years ago, in Busan, he launched a serve that clocked 163.4 mph.

Since hooking up with Aussie coach Ben Mathias in 2013, Groth has honed his skills and hardened his body. Subsequently, his results have shown remarkable improvement.

“I had to make some scheduling decisions at the end of last year,” admits Groth. “Rather than play in the Aussie wild card play-off, I decided to work really hard on my fitness and get in peak shape. I lost about five kilos and got my abs hard.

“I have to give credit to my coach, Ben. He has been a great source of motivation and has really helped me to achieve these results.

“Also, playing a more balanced schedule of ATP World Tour qualifying tournaments and Challenger main draws have given me a better perspective and improved attitude. When you are young and starting out, you dream to make it to the ATP World Tour. That is what we are all fighting for.”