Christian Horner says this season's unpredictability means F1 will have to wait until after qualifying to have a "clear indication" of who is on top in Monaco.
Thursday's practice sessions did not offer a true picture of the pecking order as pace-setter Jenson Button was the only top driver to try the Pirelli super soft tyres before the rain came down.
He finished three-tenths ahead of Lotus driver Romain Grosjean while the two Ferraris were next in line. Red Bull's best-place driver, Mark Webber, was seventh, 1.402s off the pace.
"It is so open that we will only get a better idea I would say after P3, but probably not even then," the Red Bull team boss told Autosport.
"It will probably be only after qualifying that we will get a clear indication of where we are, but the weather could be a factor as well this weekend.
"Throw that into the mix and you have a real cocktail for an entertaining weekend."
Red Bull arrived in Monte Carlo as the reigning Monaco Champions as Sebastian Vettel claimed the victory last season while his team-mate Mark Webber won in 2010.
However, Horner says that while claiming a hat-trick of wins would be great, the most important thing is to ensure a solid points-haul.
"This is a fantastic race to win," said Horner. "We have been fortunate enough to win it the last couple of years, but it is one of 20 races, and it has the same amount of points available as the others.
"The prestige here is greater than other venues but counting towards the championship it carries the same weight in points. So the most important thing for us is to maximise the package we have here.
"Hopefully we can, but whether that package can compete for the win? Hopefully it can. If it cannot we have to make sure that we optimise the best result that we can, because ultimately they will all count at the end of the year."