Pete Sampras
Age: 43 Net Worth: $150Pete Sampras is an American former professional tennis player for 15 years and was ranked no. 1 for six years in a row. Reuters

What signs do you look for that tell you an athlete might have to retire from playing his sport? After a not-so-good 2013 season, Roger Federer has started the new season strong reaching the semifinals of the first Grand Slam tournament. He may have dropped to eighth place in the Association of Tennis Professionals (ATP) rankings, but former top-ranked player Pete Sampras has no trouble believing that the Swiss athlete can make a big comeback this 2014 season.

Tennis great Pete Sampras (bottom L) of the U.S. sits in the spectator stands ahead of the men's singles final match between Rafael Nadal of Spain and Stanislas Wawrinka of Switzerland at the Australian Open 2014 tennis tournament in Melbourne January 26, 2014. REUTERS/Jason Reed )

According to Sampras, Federer could play for another three or four years, The Guardian reported. He said that Federer might even win a major title. As of present time, Federer has won a total of 17 Grand Slam titles.

Sampras, who will play Andre Agassi in an exhibition match on March 3 in London, said that even though Federer struggled in the past, he can see the Swiss athlete building momentum from those struggles to rise up and work on achieving success.

"I do think he can win another major," said Sampras.

However, Sampras stated that Federer has to play better to win a tournament.

"Everything needs to fall into place and he needs to play well, but he can do it. That's why he is playing. I don't think he's playing for anything else but to win some more majors and Wimbledon is the most likely."

Indeed, Federer must really be driven and motivated to win a tournament, play better, and enhance his skills. CBC.ca wrote that Federer is optimistic that he will be able to compete in the 2016 Olympics in Rio de Janeiro.

Roger Federer of Switzerland reacts during a news conference after his men's singles semi-final match against Rafael Nadal of Spain at the Australian Open 2014 tennis tournament in Melbourne January 24, 2014. REUTERS/David Gray

"I have to make sure that I take care of my schedule, of my body, of my mind," said Federer. "Hopefully I can still stay on tour for many more years and hopefully play the Olympics here in three and a half years or so, so I have to look far ahead and not just the next six months," he added.

Federer is now 32 years old. Sampras retired from playing when he was 31 years old, after he won his 14th Grand Slam title at the U.S. Open 2002.

Federer may have dropped to the eighth place in the ATP World Rankings, but Sampras feels that the Swiss athlete still has got it in him, unless of course, Federer can no longer compete at his best. Sampras ponders that the time Federer would stop playing is the time that the Swiss athlete slides "far down the rankings."

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