McLaren's Jenson Button says he believes Lotus are favourites to win the Monaco Grand Prix this weekend.
Button was fastest in second practice from Lotus's Romain Grosjean, but was the only driver to use the faster of the two types of tyre before rain.
"The cars that look very fast to me are the Lotuses," Button said.
"If you look at the runs, when they're out, they're very competitive, so I would say the Lotus is probably the car to beat this weekend."
Button's team-mate Lewis Hamilton, who was fourth fastest in the first session in the morning and 11th in the second, echoed those views.
He also predicted Red Bull would be competitive despite Mark Webber and Sebastian Vettel having low-key days, with their highest position being seventh by Webber in the second session.
"I think the Lotus is massively quick," Hamilton said. "Not really quite sure what the Red Bull is up to but I'm sure they'll be quick. The Ferrari is very quick."
Ferrari's Fernando Alonso was fastest in the first session and fourth quickest in the afternoon - and Grosjean said he expected the Spaniard to be a major force in Saturday's qualifying session and Sunday's race.
"Fernando in Monaco is always something special," Grosjean said. "They have a pretty good car now."
Grosjean added that he was confident of a strong showing in Monaco.
"We had a good day," he said. "The car is working pretty well, the baseline is good as well.
"It's always good to be in front in Monaco and get in some good laps. You really need to be confident with the car and we are on a good way to achieve that.
"I enjoy driving in Monaco, the feeling is unbelievable, playing with the guardrails.
"I did enjoy the day, the car is suiting me pretty well as well. I think we are on the way to know how we need to have it."
"For sure we will try to do everything to put it on pole. We are working quite well at the moment, but there is a lot of work to do and the others are not giving up."
Hamilton pointed out that Grosjean's time was closer to Button's than the performance differential between the two tyres, the 'prime' or 'soft' tyre and the faster but less durable 'option' or 'super-soft'.
Button set a lap of one minute 15.746 seconds, while Grosjean was 0.392 secs behind.
Hamilton said: "I don't think Jenson's time would be fastest.
"They say there's about six or seven tenths between a prime [tyre] and an option, and the Lotus did a 16.1 on the prime so if they put that on it means they are a little bit quicker.
"But I think Jenson has more time in him and there's more time in the others as well. I think we're in a good position nonetheless."
Button said he was reasonably satisfied with his car.
"The car has improved from first to second practice," he said.
"There was something with the car I didn't like in P1; we tried something different and it works. So I am happy with how the car feels but we're still not there yet.
"We were quickest but we were one of the only guys to do a lap on the super-softs.
"I don't think it's massively quick but the car feels OK, there is a lot of room for improvements we can make.
"It's not that we have a problem and don't know where to go from there. We know what direction to go."
Despite Hamilton's expectation that Red Bull would be competitive when it mattered, Webber said the team were struggling.
"It was not easy for us," the Australian said. "We have got some work to do in the next 24 hours. There are clearly some very quick cars and we have to improve our car."
Asked if he had a chance of pole position on Saturday, Webber said: "It will be very difficult. We have work to do."
Alonso said: "The first impressions are quite positive. We only made a few small modifications to the set-up, trying to improve it, but it's too early to draw conclusions.
"The weekend has got off on the right foot for us; now we must try to keep going down this path."