Niki Lauda has hailed the Ferrari versus Mercedes duel for the 2017 world championship.

So far this year, Lewis Hamilton and Sebastian Vettel have each won two grands prix, and are separated in the standings by just six points.

That duel culminated in the recent Spanish Grand Prix, which Lauda said he enjoyed watching.

"It was racing at the highest level," the Mercedes team chairman told Blick. "It does not get any better. Pure fascination.

"A four-time world champion and a three-time world champion fighting for Ferrari and Mercedes in the two best cars in the world. There is no better advertising for the sport."

Lauda said that he thinks that battle will continue all the way through the year.

"Sure - the rest cannot keep up. It's as simple as that," said the Austrian.

Meanwhile, he thinks that Vettel and Hamilton's respective Finnish teammates, Kimi Raikkonen and Valtteri Bottas, will play important supportive roles.

"Raikkonen and Bottas will probably play a decisive role for Ferrari or Mercedes winning the constructors' world championship," said Lauda.

"I would say Bottas is now as good as [Nico] Rosberg was. And maybe a bit better than Raikkonen."

In that way, he hopes it is the drivers rather than the cars that determine who is crowned champion in the end.

"Reliability is important in every world championship," said Lauda. "The turbo problem Bottas had in Barcelona hurts us. Now our well-known English-German quality control will have to improve.

"We do not want a world championship of technical failures."

The championship continues on Sunday with the Monaco Grand Prix.