ATP World Tour Finals: Four rival venues for London showpiece
London faces competition from "four other regions" for the right to stage the ATP World Tour Finals from 2016.
ATP chief Chris Kermode told BBC Radio 5 live Sport that discussions about the future venue of the season-ending tournament are currently taking place.
"We've got interest from four other regions and we'll make a decision by March or April," said Kermode.
The Tour Finals, for the world's top eight players in the men's game, runs from 9 November at the O2 Arena.
It has been held at the London venue since 2009 and has a contract to remain there until 2015.
Roger Federer, Novak Djokovic and Rafael Nadal have all qualified for the eight-day event, but Andy Murray has yet to secure his place.
You can hear more of Kermode's interview with Jonathan Overend in Sunday's 5 Live Sport from 12:00 BST.