Mercedes motorsport boss Toto Wolff admits there was one weekend where had a doubt over Lewis Hamilton's ability to perform during 2018.

While the Briton was on his ultimately successful mission for a fifth world championship, he combined it with launching his first fashion collection in collaboration with Tommy Hilfiger.

That meant Hamilton was putting in additional travel onto his schedule in addition to the already packed F1 calendar and it did lead the Mercedes chief to question his preparation for the Singapore race.

"He flew to Shanghai and then to New York prior to the Singapore Grand Prix and, to be honest, we did have our doubts about it," Wolff told Dutch publication Formule 1.

However, Hamilton soon put those concerns to bed.

"When he put in that mega lap in qualifying, I knew enough," the Austrian added.

Indeed, his pole lap around Marina Bay was considered one of if not the best of the season on a circuit that historically hasn't suited Mercedes and set him up for victory in the race.

Hamilton has also been giving his boss other heart attacks after testing a Yamaha superbike around Jerez just a week after last year's season finale and this past week alone has posted pictures of himself sky diving and surfing.

Toto will be hoping he's wrapping in cotton wool between now and March.