Tomas Berdych climbed to a new career high No. 5 in the world on Monday as the latest ATP singles rankings were released following tournaments in Dubai and Acapulco.

Berdych reached the finals at Dubai, where he lost to Roger Federer. Berdych is now 16-3 on the season.

Also moving up one spot is Andy Murray, back to No. 6 in the world, as Juan Martin Del Potro slid two spots down to seventh. Those three men will likely change positions often through the season. Currently just 20 points separates them - Berdych has 4,890 points; Murray 4,885 and Del Potro 4,870.

Dubai champion Federer did not gain any places in the standings, but he moved within striking distance of a return to the Top 5; Federer is still eighth with 4,625 points.

The chasms remain in the Top 10 between No. 1 Rafael Nadal, No. 2 Novak Djokovic and the rest of the field. Djokovic is No. 2 with 10,260 points, nearly 5,000 more than No. 3 Stanislas Wawrinka.

In the top 20, South Africa's Kevin Anderson, the third-tallest man to ever play pro tennis at 6'8", rose three spots to a career-best No. 18 after reaching the finals at Acapulco.

He lost there to Bulgaria's Grigor Dimitrov, who soared into the Top 20 at No. 16. At 22 years, 10 months of age, Dimitrov is now the youngest man in the Top 20, supplanting Milos Raonic and Jerzy Janowicz (both are 23).

There were no changes in the women's Top 10, although just outside of it Dominika Cibulkova rose to No. 11 from 13th and Caorline Wozniacki fell one spot to No. 12.