Kei Nishikori has consolidated his place in the top eight ranked players of the world for the first time after his breakthrough 2014 season where he reached the final of the US Open Championships. He will make his second appearance in the ATP World Tour Finals this year.
Despite this tremendous feat, Nishikori's season this year has fallen short of his stellar successes of 2014. However, this year has not been ordinary either, bearing him three ATP titles and two Grand Slam quarterfinals.
He started the year off positively, reaching the quarterfinals of the Australian Open and losing to the defending champion Stanislas Wawrinka. In February, he defended the Memphis Open title once again and became the first ever player to win the title three times in a row.
He also showed some mastery on clay as he defended his title at Barcelona and reached the quarterfinals of the French Open for the first time in his career. However, this form would not overlap into his grass court season as he suffered a calf injury which forced him to pull out of Wimbledon in the second round.
Nishikori regained some form in the hard court season as he won the Citi Open, beating home favorite John Isner in the final. However, fatigue coupled with hip injuries ruined the rest of his hard court season and caused him to crash out of the US Open in the first round against a spirited Benoit Paire.
Nishikori can look at this year's ATP World Tour Finals as an opportunity to make a lasting mark on 2015 which has been thus far lacking from his side. He made an extremely strong showing last year by winning two of his round robin matches and taking Novak Djokovic to three sets in the semifinals, and this will give him confidence.
Even though he faces tough opponents in the form of Djokovic, Roger Federer and Tomas Berdych, the Japanese is one whom we can never count out against the world's best. He has a winning record against Berdych, and has performed well against both Federer and Djokovic in the past. He certainly has the skill set to test the opponents of his group. The question is whether he is mentally strong enough after a year without any riveting performances to do so.