Andy Murray’s $2.8 million gamble.

But the ATP won’t have a bar of it.

Murray inspired Britain to victory over Australia in the Davis Cup semi-finals, securing their first appearance in a final since 1978 with a straight-sets defeat of Bernard Tomic in Glasgow on Sunday.

Belgium are expected to stage the final on clay and with the hard-court World Tour Finals not due to finish until the week before, Murray is thinking about sitting out the prestigious event at London’s O2 Arena.

“The O2 would obviously be a question mark for me if we were playing on the clay,” Murray, a two-time World Tour Finals semi-finalist, told BBC Radio 5.

“I would go and train and prepare on the clay to get ready for the (Davis Cup) final. You saw last year with Roger Federer that the matches at the O2 are extremely tough and physically demanding.

“If you reach the final and play on the Sunday, you also need to take time off. You can’t just play five matches against the best players in the world and then not take any days off.”

However, ATP president Chris Kermode — a long-time ally of Murray’s — has since made it clear his organisation is expecting the 28-year-old to participate at the O2 from November 15-22. “The Barclays ATP World Tour Finals is a mandatory event on the ATP World Tour and all players who qualify, unless injured, are required to compete in the event,” he said in a statement.

“He has had a fantastic season and earned his place among the world’s top eight players to compete at the season finale.

“We are aware of the comments made after the Davis Cup tie in Glasgow, however our expectations are that, if fully fit, Andy would compete in this year’s tournament.

“Unless we hear otherwise via an official withdrawal, he is still entered to compete at the O2.”

Missing the World Tour Finals would also oblige Murray to forego prize money ranging from $465,800 to $2.8 million for a player who goes through the tournament unbeaten, as well as 1,500 ATP ranking points.

Andy Murray celebrates winning his Davis Cup match against Bernard Tomic.Source:AP

His 7-5 6-3 6-2 victory over Tomic gave Britain an unassailable 3-1 lead, with Thanasi Kokkinakis’ win against Dan Evans in Sunday’s final singles rubber making the final score 3-2.

Belgium, who defeated Argentina 3-2 in the other semi-final, will host the final on November 27-29.

Murray, 28, won both singles matches as well as the doubles with elder brother Jamie, and revealed afterwards that a back injury sustained in training had dogged him throughout the tie.

“My back had been giving me a lot of trouble this weekend and for a few days before the tie as well,” the world No. 3 said.

“The previous issues I’ve had with my back have been completely different. My back was fine during the US Open and all through that stretch.

“I took five days off and started practising again. On Tuesday night, once I had finished practising and had cooled down, my back was extremely sore and it got progressively worse over the next couple of days.”

Victory puts nine-time winners Britain, on the verge of relegation to Zone Group III five years ago, a step closer to an historic first title triumph since 1936.

Murray is now looking to become only the fourth player ever to win the Davis Cup, Olympic gold and multiple grand slams.

“We have an opportunity to win the event in the next match, but there’s so much tennis still to go,” said the former US Open and Wimbledon champion.

“We still need to win three matches and there’s two or three months until the next tie, and a lot can happen between now and then.

“It would be an incredible achievement to win it, but there’s a long way to go.”