Rory McIlroy hit back at Nick Faldo after the six-times major winner told the Northern Irishman earlier in the week that he had to devote more time to golf.
McIlroy has had a troubled season after changing clubs at the start of the year following the signing of a mega-bucks deal with Nike and he was clearly irritated by Faldo's comments.
"He said I should be at the course nine to five," the world number two told reporters on the eve of the 142nd British Open at Muirfield.
"I actually was on the range at 6.15 (yesterday) and got out of the gym at 6:15, a 12-hour day compared to his eight-hour day.
"Nick should know how hard this game is at times and he's been in our position before. He should know how much work that we all put into it."
"I think he has to remember how hard this game can be at times" - Rory McIlroy
Englishman Faldo, who turns 56 on Thursday and is playing in the Open this week for the first time in three years, hinted on Monday that McIlroy was spending more time than he should on off-the-course activities.
"You have a window of opportunity, that's my only words of wisdom to Rory," said the veteran who now works as a full-time television commentator. "You have say a 20-year window as an athlete - concentrate on golf, nothing else.
"Hopefully you have another 40 years to enjoy it so just concentrate on your golf."
McIlroy acknowledged that Faldo was not trying to unduly criticise him.
"He probably said a million other things in that interview," said the 24-year-old. "He obviously said something about me and that's the thing that's been picked up by everyone.
"I know how these things go, I know he wasn't trying to get on my case at all. He was just offering words of advice in some way.
"(But) I think he has to remember how hard this game can be at times."
McIlroy is without a victory since the DP World Tour Championship in Dubai in November, a win that made sure he ended the year as the number one golfer in Europe and the United States.
"I think the game's like life, you're going to go through highs and you're going to go through lows. It's just about trying to work your way out of the lows," said the twice major winner.
"I haven't played my best golf this year but I've showed signs that it is there. It's just a matter of trying to do that more often.
"Sooner or later it will turn around and I'll play the golf that everyone knows I'm capable of and the golf I know that's capable of winning major championships," said McIlroy.
McIlroy has left no stone unturned in his bid to prepare for this week's event at Muirfield.
"I played 18 holes last Monday and then 27 on Tuesday," he explained. "Then I played 18 this Sunday, 18 on Monday, 18 yesterday and I'll play nine today.
"That's a lot of holes. I've also got a new driver in the bag...it's a different head shape, more of a pear shape, but it encourages the club face to close a little bit more.
"My bad drive this year has been losing it to the right so this is encouraging the club face to square up on impact and obviously I'm not getting that right shot anymore which is a huge plus."