Mercedes F1 chief Niki Lauda feared for Nico Rosberg's momentum

Rosberg scored the ninth win of his F1 career as he controlled the race from pole position at Barcelona's Circuit de Catalunya, finishing 17.5 seconds clear of Mercedes team-mate Lewis Hamilton.

With the gap to Hamilton cut to 20 points heading into his home race in Monaco in a fortnight, Mercedes non-executive director Lauda told AUTOSPORT: "For the first four races Lewis was ahead, he blew Nico off the track.

"But now Nico has fought back, I would say he is totally back, and for the team and for him this is good.

"My worry was if he hadn't have driven well here then he would have lost some momentum in his head, so thank God it's back.

"He is back to last year's performance level, and now we are back to this team spirit again, which is good for the development of the car and for the whole team."

Crucial for Lauda was the 45-second gap between Rosberg and third-placed Sebastian Vettel in his Ferrari come the chequered flag after 66 laps.

Ferrari remains Mercedes' closest rival, but it is clear the German team will now take some stopping after a 14th one-two for Rosberg and Hamilton as a pairing.

"I was worried here Ferrari would catch us because nobody knew what upgrades they would bring, but again we're ahead, so very good," added Lauda.

Mercedes motorsport boss Toto Wolff believes the result felt more like a "P1 and P1" given Hamilton's performance during the race.

The reigning champion complained of set-up issues throughout the weekend, and after a poor start and then a wheel-gun issue at his first tyre change that forced the team to switch to a three-stop strategy, Hamilton put in a charge to finish runner-up.

"On a three-stop, with the compromised start, a compromised pit-stop, finishing P2 is really great driving from Lewis," said Wolff.

"Both of them were faultless in the race. It is extremely satisfying we can pull it out when things aren't running perfectly. "