BAKU, Azerbaijan — It was an unknown circuit but a familiar scenario in Friday practice for the European Grand Prix with Mercedes dominating its rivals as Lewis Hamilton topped the time sheets ahead of teammate and championship leader Nico Rosberg.

The bumpy, windy and low-grip Baku street circuit saw drivers regularly running up escape roads and clipping the walls, yet the hope of Mercedes' rivals that the unique layout would bring them back into contention seems in vain.

Hamilton hit a wall and missed the end of the opening session due to excessive tire wear, but at the end of session two his time of 1 minute, 44.223 seconds was seven tenths of a second ahead of Rosberg, who was robbed of a chance to respond late when he suffered an engine failure.

The strong challenges that Red Bull and Ferrari had put up in the previous two races at Monaco and Montreal, respectively, had promised a tighter contest in Azerbaijan, but their threat was glaringly absent.

Red Bull's Daniel Ricciardo snapped off his right rear wheel when sideswiping a trackside barrier in the opening session, and impressively rapid repairs got him on track for the start of the second session, but he finished 10th, more than two seconds off Hamilton's pace.

His teammate Max Verstappen suffered a clutch-related oil leak which kept him in the garage for most of the morning session, and he fared only a couple of tenths better than his teammate and was seventh fastest.

"The track is really challenging and that's a good thing," Ricciardo said. "Combined with the low level of grip it definitely makes it hard to find a good setup. I don't think we found that today."

While Red Bull had its excuses and was not expected to push Mercedes here due to its struggles on circuits with long straights — the main drag here is the longest in F1 at 2.1 kilometres (1.3 miles) — Ferrari was more disappointing.

Kimi Raikkonen was 2.4 seconds off the pace in 13th and Sebastian Vettel not much better in eighth, though the German did deliver the line of the day in a radio message to his pits while stuck behind the McLaren of Fernando Alonso: "I'm losing tire temperature like crazy because Alonso's taking a bus tour around Baku."

Raikkonen had a failure with the MGU-K energy storage system late in the second session and Vettel was then brought in as a precaution.

"It's been a tricky day for us, perhaps not entirely clean when you look at raw pace, but then again it's Friday so there is no need to worry too much," Vettel said.

Tires were at the centre of attention through the opening session due to a number of cuts in the rubber caused by the overlapping metal curbs and loose bolts within them.

Tire provider Pirelli reported the issue to the FIA which ordered hasty repairs between sessions, and that caused the postponement of the scheduled GP2 qualifying. Roberto Boccafogli from Pirelli confirmed the cuts, but said they were not deep enough to cause air loss.

With Red Bull and Ferrari struggling, it was Mercedes-powered Force India and Williams that were the best of the rest, with both teams flourishing on the long straight. Williams' Valtteri Bottas reached 351 kph (218 mph) approaching Turn One. Force India's Sergio Perez was third fastest overall and teammate Nico Hulkenberg was fifth, with the pair separated by Bottas.

Toro Rosso's Carlos Sainz Jr. was sixth and McLaren's Jenson Button was ninth.