By Nick Georgandis
Japan's Kei Nishikori's victory at Memphis on Sunday catapulted him up six spots in the latest ATP rankings, to No. 16 in the world, one spot short of his career-high. The 23-year-old Nishikori defeated Feliciano Lopez in straight sets and never lost a set over the tournament as he improved to 11-2 on the year. It's his first-ever indoor title and second in as many years after winning Tokyo in 2012. Nishikori defeated Croatia's Marin Cilic in the quarterfinals, but it was enough for Cilic to move up one spot to No. 11 in the world. It's the highest the 24-year-old Cilic has been ranked since May of 2010. There were no changes in the Top 10, but plenty in the Top 25, where Milos Raonic fell four spots to No. 18 and American Sam Querrey dropped two spots to 23rd. There was one giant leap and one giant plummet in the Top 50. The leap came from Russia's Denis Istomin, who soared 21 spots to No. 42 following his trip to the Memphis semifinals that included a first-round upset of No. 16 John Isner. Istomin squared his all-time record at 113-113 and is within 10 spots of his career highwater mark of No. 33. Taking a swan dive the other way was Austria's Jurgen Melzer, who dropped 22 spots to No. 49 following his first-round defeat at the hands of Igor Sijsling in Memphis. Although he earlier reached the finals of Zagreb, Melzer is just 7-7 on the season and has fallen off considerably from the form that landed him in the Top 10 for 13 straight weeks two years ago.
There was only one change in the WTA top 10 this week, as Petra Kvitova switched places with Sara Errani, taking over as the new No. 7 in the world. Kvitova took Errani's spot by defeating the Italian in the finals at Dubai with a 6-2, 1-6, 6-1 victory. It's the first title of the year for the 22-year-old and the 10th of her career. She improves to 12-5 on the season. In the top 20, the endless shuffle of Dominika Cibulkova and Maria Kirilenko continued, with Cibulkova reclaiming No. 14. Roberta Vinci changed places with Sloane Stephens, with the American teenager dropping back to No. 16. Two former Top 2 players made moves in the Top 25. Venus Williams moved up one spot to No. 20, while former No. 1 Jelena Jankovic Jankovic won Bogota on clay against an admittedly inferior group of talent - taking out No. 198 Paula Ormaechea in the finals and not facing a player ranked higher than 96th during the week.