Former British number one Greg Rusedski believes circumstances prevented Roger Federer from becoming the world number one.

Federer outclassed Rafael Nadal in the final of the Shanghai Masters on Sunday (15 October) to win his sixth title of the year.

It was not only the Swiss ace's fifth victory in a row over Nadal but also put him less than 2,000 points behind the world number one in the ATP tennis rankings in second.

Speaking on the match-up and the manner in which it went, Rusedski claims the speed of the court overwhelmed the Spaniard who had no answer to Federer's gameplan.

"I really didn't feel like, on this surface also being indoors, the speed of the court – it was just too quick for Rafa, it didn't buy him any time," Rusedski said, as quoted by the Metro.

"If you're going to beat Roger at the moment, you have to be able to make a hole through him. We saw with Del Potro yesterday, the big serve, the big forehand pushing Roger around but Roger still found a way and with Rafa, tactically, he doesn't know what to do.

"And at the moment, this year, Roger has felt completely comfortable playing Rafa and knows exactly what he needs to do. Rafa doesn't have a clue what to do to beat Roger because he had a set game-plan that worked for over a decade and now it doesn't work anymore."

Federer tweaked his back during the Rogers Cup in Montreal in August which saw him lose the final to Alexander Zverev. The injury also played a role in the 35-year-old's quarter-final exit in the US Open to Juan Martin del Potro — an event that Nadal would eventually win.

"The other thing that is interesting, imagine if Federer wouldn't have got injured in Montreal going into the US Open," Rusedski added. "He would probably be leading the race for world No 1."

"Roger, even though it looks like he probably can't do it, still has a mathematical chance to be able to get to world No 1. But he also wants to stand to Rafa and say 'you might be No. 1 but I've beaten you now four times in a row this year as well as five times in a row' – something he'd never done."