Damon Hill believes Lewis Hamilton's busy lifestyle played a role in his Spanish GP display, adding he may have underestimated Nico Rosberg.
Hamilton made a blistering start to the defence of his Drivers' crown as he won three of the first four races and also started all four grands prix in pole position, but he was second best in Barcelona.
Rosberg proved that there is still plenty of life left in the Championship fight as he claimed pole and took the Spanish GP victory to reduce his Mercedes team-mate's lead in the standings to 20 points.
In an interview with Britain's Daily Express, Hill said Hamilton probably lost a bit of focus after his good start.
"I got the sense that Lewis slightly took his eye off the ball in Spain. Nico went home [between races] and said, 'right, I’m not having any more of this’ and focused on the next job," he said. "But look at the schedule Lewis indulged in between Bahrain and that race. He went to film in Italy, then went to the Mayweather fight – and jet lag is very debilitating and you cannot be on your best form.
"Even with someone with an abundance of talent like Lewis, to be absolutely at the sharp end you cannot afford to give anything away to someone like Nico. You should never underestimate your competitors.
"The impression Lewis gives is that he wants to enjoy his life – he has been successful and he wants to enjoy all the fruits of fame and that’s great. But his first task is to win races, that’s where everything comes from.
"What he has to do is work out what's at stake. He is on target to become one of the most successful racing drivers. It’s whether you want to dedicate yourself to that task and play afterwards."
Hill also warned that Hamilton probably gave Rosberg some ammunition with his comments after the Bahrain Grand Prix.
"Lewis said something along the lines of, 'I don’t see anyone being a threat within the team'. These sort of comments come back to bite you. I was surprised as anybody at Nico’s weekend but sometimes Lewis lets his confidence get the better of him.
"When you create an impenetrable image and it is damaged in some way, that’s more damaging than if you accept that it’s going to be tough to win. He said after the race that he doesn’t expect to win everything – well he didn’t say that before the race did he? And it’s more painful when that happens.
"Now we have Monaco coming up and the memory from last year is that Nico did a 100 per cent brilliant job all weekend and dominated the event. Now he is going into the race coming off the back of a victory.
"If I was competing I would certainly reassess my challenger. Lewis got the start to the season which he didn’t get last year but you can never afford to relax for a minute."