Judy Murray has praised Ivan Lendl's impact on her son's tennis career.
Andy Murray won his first Grand Slam title in 2012 - a victory at Flushing Meadows in September - under Lendl's guidance.
The British Fed Cup team captain told BBC Sport: "He's been a crucial factor in Andy's improvement and success this year.
"The wonderful thing about Ivan is that he's very similar in character to Andy, not least they have the same awful sense of humour! But seriously, he's very driven, very dedicated and he absolutely has his eyes on the prize.
"He's got a real sense of direction, a real toughness and he's really helped Andy with the mental side of the game, about being able to reset if you suffer a disappointment, a bad call or a run of bad games. That's allowed him to play his best tennis for much longer periods of time."
The 25-year-old also won gold at the Olympics and finished third in the BBC's Sports Personality of the Year award.
