Serving improvement pleases victorious Kei Nishikori

Kei Nishikori has admitted that he was pleased with the way that he served during his clash against Tomas Berdych at the ATP World Tour Finals in London this afternoon.

On Sunday the Japanese number one struggled to land his first serve during his 6-1 6-1 loss at the hands of Novak Djokovic.

However, he improved today to record a 7-5 3-6 6-3 victory against Berdych, which has kept alive his hopes of reaching the semi-finals.

"[My serving] was good. He has a great return so I tried to make a lot of first serves, which I think I did really well - better than the first match. I had more confidence today," he said during his post-match interview.

The 25-year-old will now take on Roger Federer in his final group game on Thursday.