Andy Murray admitted to pre-match nerves in his first outing since clinching the world No 1 ranking but at the end of his Paris Masters final here against John Isner the result was what we have come to expect in recent weeks.

Murray won 6-3, 6-7, 6-4 to claim his eighth title of the year and the 43rd of his career to win this tournament for the first time. It was his 19th victory in a row and his fourth successive title following his triumphs in Beijing, Shanghai and Vienna. His remarkable run goes back even further: since May he has reached the final of 11 of his last 12 tournaments and won eight of them.

The Scot knew on Saturday, as a result of Milos Raonic’s withdrawal from their semi-final because of injury, that he would rise to No 1 in Monday’s updated world rankings list. He replaces Novak Djokovic, who has led the rankings for the last 122 weeks.

“I felt really nervous before the final,” Murray said after a victory that means Indian Wells and Monte Carlo are now the only two Masters Series tournaments he has not won.

“I didn’t feel flat, or anything like that, which was the most pleasing thing about today for me. Obviously it’s great to win, but sometimes after you achieve something big or something that you maybe didn’t expect, it can be quite easy to have a let-down and feel a little bit flat.”

Murray, who said he had received more messages of congratulation on Saturday for not playing a match than he ever had for winning one, was not sure whether reaching the top of the rankings had sunk in yet.

“It certainly feels different to when I won Grand Slams or the Olympics,” he said. “Maybe that’s just because of the way it happened. When you play a final, you win or you lose, whereas with the No 1 ranking, it’s not really like that.”

If Murray had lost the final he would have led Djokovic by just five points in the rankings, but this victory – and the 400 extra points he has earned as a consequence – will strengthen his chances of finishing the year as world No 1.

The American worked Murray hard but it wasn't enough to deny the Scot (Getty)

At the end of this month Murray will lose the 275 ranking points he earned for winning the Davis Cup last year, but he will hold on to No 1 if he at least matches Djokovic’s performance at the year-ending Barclays ATP World Tour Finals, which begin in London next Sunday. Djokovic, nevertheless, would reclaim the world No 1 position if he wins the title and all his round-robin matches at the O2 Arena.

Isner, who has now lost all three of his Masters Series finals, had not beaten Murray in any of their previous seven meetings. Remarkably, he had only ever converted one of 34 break points against the Scot, a record which was extended here as he failed to take any of his six break-point opportunities.

The 6ft 10in American relies heavily on his huge serve. He has struck more aces this year than any other player and went into the final having hit 88 in his first five matches at this tournament.

In the light of Murray’s athleticism, Isner clearly knew that his only chance would be to attack. From the start he went for his shots and often troubled Murray with his huge forehands and punched volleys. Murray, however, soaked up everything Isner could throw at him, hit some great passing shots when Isner charged into the net and took his chances when they came.

Murray’s first competitive point since clinching the No 1 spot ended in a double fault, but it did not take long for normal service to be resumed. The Scot hit an ace on the next point and at 3-2 broke for the first time as Isner hit a backhand long.

In the next game, nevertheless, Isner forced two break points with some aggressive hitting. On the first the world No 27 appeared to be in command of the point until he was undone by a moment of typical Murray genius. Although he was forced to stretch for the ball, Murray hit a superb lob over the giant American and followed up with a winning volley.

Murray soaked up everything Isner could throw at him, hit some great passing shots when Isner charged into the net and took his chances when they came (Getty)

Murray served out for the first set and appeared to be in no trouble in the second until he served at 3-4. Isner forced four break points, only to run into a brick wall as Murray defended superbly. The set went to a tie-break, in which Murray double-faulted to go 4-2 down. On his second set point Isner hit an inside-out forehand winner which clipped the line.

Isner saved break points in the first and third games of the deciding set, but when he served at 4-5 the pressure finally told. At 30-30 Isner found himself under bombardment from Murray on two successive points and on both occasions he missed backhand volleys to hand the Scot victory.

Ivan Lendl, Murray’s coach, who has not worked with him since the US Open, will rejoin the new world No 1 in London on Wednesday. “I’ll sit down with my team and look at what my schedule is going to be for the beginning part of next year and set some goals, probably through to March time,” Murray said.