HONG KONG: Ivan Lendl on Wednesday played down Andy Murray’s chances of sealing back-to-back Grand Slams at the Australian Open, warning it was “very, very difficult to succeed” in a highly competitive era.

Lendl has coached Murray to Olympic gold and the US Open title, ending Britain’s 76-year wait for a men’s Grand Slam singles win, but he said it would be tough in January with the world’s top four all expected to be in action.

“Tennis is a very difficult sport to win these days with the likes of (Novak) Djokovic, (Roger) Federer and (Rafael) Nadal and Andy in that group –– it’s very, very difficult to succeed,” Lendl said, when asked about Murray’s chances in Melbourne.

French Open champion Nadal missed much of the season just ended with a knee injury, easing the task of his rivals, but is now back in training.

Djokovic won this year’s six-hour Australian Open final against Nadal, and this month he dominated Federer to clinch the season-ending ATP Tour Finals.