Roger Federer has been backed to make a strong comeback in 2018 despite suffering massive disappointment after being knocked out in the semi-finals of the ATP World Tour Finals in London.

The Swiss ace was favourite to win the title at the O2 Arena and sailed through into the last-four without losing a single match, and former American tennis star Peter Fleming believes that will be the main reason for the massive disappointment.

David Goffin was Federer's conqueror in the semi-finals – a match the latter was favourite to win. The 36-year-old, who was looking for his eighth title of the season, had beaten Marin Cilic, Alexander Zverev and Jack Sock on his way, but was unable to beat the Belgian despite taking the first set 6-2. He lost the next two 6-3, 6-4 to bring his 2017 campaign to an end.

Fleming, a seven-time men's doubles Grand Slam champion, feels that Federer will be disappointed in the manner of his exit, but is confident that it won't hamper his form going into the new season in under two months' time.

The 19-time Grand Slam winner has gone through bigger disappointments in his career and comeback stronger with the most recent being his injury absence in 2016, when he was forced to miss the last five months of the season due to a knee injury.

"A huge disappointment really," Fleming said while talking about Federer's exit, as quoted by the Express.

"I'm sure that because everybody had picked him (to win), that means probably nothing to him, but he was undefeated coming into the semi-finals against all three opponents.

"He had to think, 'Alright, this is pretty good, just play your best tennis or somewhere near it and you're good to go.'

"Yeah, he'll be disappointed but he's had bigger disappointments I think during his career and he's come back even stronger. So he will be alright I think in the end," the American doubles star added.

Goffin, however, was unable to take his momentum from the Federer game into the finals as he succumbed to Grigor Dimitrov in the summit clash on Sunday, 19 November, as the 2017 tennis season came to a close.

Roger Federer
Roger Federer 's 2017 season ended following his loss to David Goffin in the semi-finals of the ATP Finals Getty