Boris Becker has backed Roger Federer to continue his rich vein of form and go on to win 20 men's singles Grand Slam titles before he calls time on his career.

The Swiss ace's future in the game was called into question after he missed six months of last season with a knee injury. Even before that, Federer had failed to win a Grand Slam title since his triumph at Wimbledon in 2012.

The 35-year-old, however, turned back the clock following his injury return in January this year and is only behind Rafael Nadal in the singles race in 2017. Federer has played some of his best tennis which includes a reinvented backhand.

The former world number one has won three of the four tournaments he played which included his 18th Grand Slam title in Australia and back-to-back Masters Series titles in Indian Wells and Miami. Federer then took a 10-week break and skipped the entire clay court swing of the season before returning for the start of the grass court season at the Mercedes Cup in Stuttgart.

He lost in the first round in Stuttgart against veteran Tommy Haas, but has made it to the semi-finals of the Halle Open as he continues preparing for the Wimbledon Championships starting on 3 July. Federer has made it clear that winning Wimbledon is his next big target for the season, and Becker believes there's no reason why he cannot challenge for the title at SW19 and add to his tally before the end of his career.

"He is Roger Federer – the name speaks for itself. He has defied the odds many times in his life before, and he's spent 300 weeks at No 1 in the world rankings," Becker said, as quoted by the Mirror.

"He has always done things the Federer way and he has rejuvenated the sport. It's great to see 35-year-olds competing against everybody younger and it's one of the great stories of the year.

Roger Federer
Roger Federer is among the favourites to win his eighth Wimbledon title when it gets underway on 3 July Getty

"Roger is refusing to grow old, and if he believes a 19th Grand Slam is possible, then why not a 20th as well?" the German three-time Wimbledon champion added.