Sergio Perez sees Fernando Alonso and Ferrari as the threats in Monaco

Champions Red Bull have won all five races so far, four of them with one-two finishes, but Monaco's tight and twisty street circuit -- the slowest on the calendar -- gives rivals a fighting chance.

Alonso, whose last win was a decade ago with Ferrari, has finished third in four races this season and is the best of the rest after Red Bull's championship leader Max Verstappen (25) and Perez.

He is also a two times winner in Monaco and feels his current car will be well suited to the challenges of the principality, while the Red Bull enjoys less of a speed advantage.

"We certainly know that it’s not our strongest circuit," Perez told reporters. "But we will see. It's still Monaco and anything can happen.

"Certainly. I think Fernando, the Ferraris, I do expect them to be quite strong as well, like they were in Baku," added the Mexican when asked who posed the biggest threat.

"Obviously over one lap around this place they will be strong. So yes, I do expect them to be quite strong. And also Mercedes can be in the mix."

Qualifying is crucial in Monaco, with overtaking near-impossible.

Ferrari's Charles Leclerc (25) has taken pole position for two years in a row in his home town but has yet to stand on the podium there.

Alonso told reporters he would be gunning for victory, although he expected Ferrari to be strong.

"I think Ferrari were outstanding in Baku and we could see another great weekend for them here," said the Spaniard.

"But then... if I tell you that I don't come here thinking that I can win the race, I will lie to you, because this is a one-off opportunity.

"We know that Monaco, Singapore, there are specific race tracks that you need to gain the confidence on the free practice, get closer and closer to the walls and yes -- I will attack more than any other weekend."