On Day Four of main draw action at the Gerry Weber Open, the first match of the day was an anticipated clash between the third seed Kei Nishikori and ATP rising star Karen Khachanov. Unfortunately, the crowd was unable to watch a full match as the world number nine was struck by injury once again.

Nishikori's participation at Wimbledon is in major doubt. The 2014 US Open runner-up has reached the fourth round at SW19 on two occasions, and it remains the only Grand Slam where he has failed to reach the quarterfinals. The Japanese star retired during the sixth game of the match, after receiving a medical timeout on his lower back.

Opportunity knocks for the world number 38 as he has a very good chance of pinching one of the seeding spots at Wimbledon, following his good showing at the French Open, where he lost to world number one Andy Murray in the fourth round, and he faces a compatriot in Mikhail Youzhny or fellow rising star Andrey Rublev in tomorrow's quarterfinal.

Nishikori retires after a closely contested few games

It seemed as though that the third seed was going to break Khachanov's serve as the 21-year-old was under pressure immediately at 15-30 on his serve. Nonetheless, he got to game point with good forehands, moving Nishikori around the court. Nevertheless, the former world number four continued to apply pressure on Khachanov's serve but the young Russian eventually held serve in a lengthy four-minute opening game with Nishikori coming forward to the net but committing a backhand volley unforced error in the net.

A medical timeout and retirement has been a recurring theme for Nishikori (Photo by Carmen Jaspersen / Getty)
A medical timeout and retirement has been a recurring theme for Nishikori (Photo by Carmen Jaspersen / Getty)

The world number nine held onto his serve with ease in the following game to restore parity at 1-1. Moreover, Khachanov continued to struggle on his own service game despite racing out to a 40-15 lead. He committed a double fault, and Nishikori produced a strong backhand down the line, forcing the error from the 21-year-old. For the second successive service game, Khachanov was at deuce but he held onto his serve by virtue of a backhand unforced error from Nishikori's racquet.

Opportunity knocked for Khachanov in the next game as he created his first break point chance of the match with a sweet half-volley winner at the net. Nishikori thought his volley was going long but he was able to save the break point with Khachanov's forehand sailing long behind the baseline. He produced a second break point chance with a sweet backhand return down the line but Nishikori saved it with a good serve down the middle, and he held serve again to level the opening set at 2-2.

For the third service game in succession, Khachanov was under pressure on his serve, and he had to stave off a break point for the first time. He found his first serve, and he saved it with some strong first serves out wide to lead 3-2.

A dejected Nishikori waved to the crowd following his retirement (Photo by Carmen Jaspersen / Getty)
A dejected Nishikori waved to the crowd following his retirement (Photo by Carmen Jaspersen / Getty)

After the conclusion of the fifth game, the third seed took a medical timeout for a lower back injury. Nishikori came out to serve, and it was evident, that he couldn't move. He trailed at 0-15 and was unable to carry on, handing the world number 38 an easy pass to the quarterfinals.