Tennis number one Novak Djokovic has been nominated again for the Laureus World Sportsman of the Year Award he won in 2015, which doesn't surprise his coach Boris Becker, who says the Serb keeps getting better. Triple Wimbledon champion Becker is Chairman of Laureus Germany, where the awards ceremony will be held in Berlin on April 18, and in a recent interview in London said that Djokovic is an incredibly motivated street fighter who keeps getting better.

"He has an incredible amount of motivation to win. You know, it's not the first time that he's winning Grand Slams, but he keeps on getting better and better. You know most players when they've won so much, they lack a little bit in hunger, in wanting to do what's necessary to win; Novak's different," said Becker.

The German added: "He was not raised with a golden spoon, to put it mildly. He was born in war-torn Serbia and they had to leave their apartment a couple of times, because bombs were over their heads. Imagine that. I think that that defines your life. That defines your character. I call him, in the best possible meaning of the word, a real street fighter. I mean you don't want to go into battle one-on-one with him, when he's ready for it. I think that that shows in his matches, that shows when he has to play five sets, that shows when he has to struggle and overcome difficulties. He's a real tough guy when he needs to be."

The world number one retired with an eye problem from his Dubai Championships quarter-final against Spaniard Feliciano Lopez last week, but is expected to play on Friday in Serbia's Davis Cup tie with Kazakhstan in Belgrade. As for becoming the greatest player ever and overtaking Roger Federer's 17 grand slams, Becker remains cautious.

"Obviously the question now everybody's asking: can Novak overtake Roger's (Federer) record winning 17 grand slams? I think, at the moment, that's far-fetched. That's not something we talk about. That's not on our agenda. That's quite frankly, not our goal. Our goal is to play this year, as well as possible, win as many tournaments, hopefully win as many Grand Slams as possible – and that's it.

"Once Novak's career is over, when he's 35, or 37 – I don't know how long he wants to play – then you talk about this, not while he's in the middle of it. Is that theoretically possible? Of course. Is he healthy enough, good enough? Of course. But, he's only got 11 (gram slam titles)" said Becker.

The other five nominees for the Laureus World Sportsman of the Year Award are sprinter Usain Bolt; basketballer Stephen Curry; F1 driver Lewis Hamilton; footballer Lionel Messi; and golfer Jordan Spieth.