Nico Rosberg reckons Mercedes could have fight on their hands this weekend after Ferrari showed "serious pace" in Friday's practices in Bahrain.
Kimi Raikkonen topped the afternoon session as the sun baked down on the Sakhir circuit while the Scuderia were right up there later that night.
Although Rosberg was quickest under the flood lights, his 1:34.647 a tenth faster than Lewis Hamilton's best, the Ferraris were not far behind.
Raikkonen's best in the cooler conditions was half a second off the pace with Sebastian Vettel a further tenth behind.
However, it was Ferrari's long distance pace that really impressed.
On the same rubber as Rosberg in FP2, there was a stage when the Finn was matching if not bettering the German's lap times.
As such Rosberg reckons Ferrari could be a threat this weekend.
"We learned that it is pointless driving at lunch time because we don't learn much because the race is in the evening and it's such different conditions," said the Mercedes driver.
"After that in the evening we learned that we were very quick on one lap again and the Ferrari is very dangerous to us on the long run because they have serious pace."
He added: "It looks like they are a genuine threat."