Mercedes\' title-duelling duo keep a wary eye on one another while training in the same gym.That is the claim of Nico Rosberg, who with his lucky third-consecutive Monaco victory closed the gap to wor

Mercedes' title-duelling duo keep a wary eye on one another while training in the same gym.

That is the claim of Nico Rosberg, who with his lucky third-consecutive Monaco victory closed the gap to world champion teammate Lewis Hamilton to just 10 points.

The pair has had an often difficult relationship as Mercedes teammates, but in their formative racing days, they were very close friends.

Rosberg explained to the German broadcaster RTL: "It's more difficult now.

"We are both so ambitious that it's not so easy anymore. We get along fine, but we are no longer best friends.

"There are some better phases when we can sometimes share a laugh together, and then there are worse phases where it is all a bit more serious," he added.

Rosberg has almost always lived in Monaco, while Hamilton is a much newer resident, having moved from Switzerland in recent years.

The Briton even moved into the very same apartment building as Rosberg.

"We see each other quite often," Rosberg explained, "as we train in the same gym.

"So we're both always looking at what the other is doing, to make sure he's not getting any advantage," he laughed.

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