Lewis Hamilton has claimed his first ever pole position in Monaco, edging out Mercedes team-mate Nico Rosberg.
The reigning Formula One world champion has endured a frustrating time in the principality, with his German team-mate getting the better of him in the last two years.
However, Hamilton's time of one minute 15.098 seconds was enough to eke past Rosberg, with Ferarri's Sebastian Vettel following home in third.
The British driver entered round six with three wins under his belt and eyeing a “perfect weekend” in Monte Carlo, where Rosberg was hoping to follow up victory in Spain last time out.
A third straight Monaco win may now be beyond the German, though, given 10 of the last 11 races here have been won by the driver starting in pole.
Rosberg had clocked the quickest time in the first two parts of qualifying, only to be pipped by Hamilton in the third after overcoming earlier problems.
The 30-year-old insists “not even half the job is done” ahead of Sunday’s race, but was understandably elated to get his maiden pole in Monaco.
“It has been a long old time,” Hamilton said. “I can’t express to you just how happy I am.
“It wasn’t the easiest session. I had a lot of things that kind of weren’t easy.
“I had a lot of things that could throw you off the rhythm and I didn’t have my rhythm until the last two laps.
“Coming across the line I was just hoping for once that you got it.
“It was incredibly special for me and for my guys who have worked so hard this weekend.”
Vettel will start third on the grid after following up an impressive run in the final practice session, while Red Bull's Daniel Ricciardo is in fourth.
Team-mate Daniil Kvyat is fifth, followed by Kimi Raikkonen of Ferrari and Force India's Sergio Perez in a surprise seventh.
The Toro Rosso pair of Carlos Sainz Jr and Max Verstappen were either side of Lotus' Pastor Maldonado in the top 10, which team-mate Romain Grosjean just missed out.
The Franco-Swiss driver will drop five places on the grid this Sunday due to a change in gearbox, boosting McLaren’s hopes of a first point of the season.
The Woking-based team have not made it into the third qualifying session this season and Button clocked the 12th fastest time in qualifying.
A yellow flag cost him valuable time on the final lap, while two-time world champion Alonso pulled up with what appears to be another mechanical issue.
The Spaniard will start behind Nico Hulkenberg and Felipe Massa of Force India and Williams, respectively.
Williams' Valtteri Bottas was a surprise casualty of the first session. The Finnish driver, so impressive when finishing fourth in Spain, could only come home 17th, locked between the Sauber duo of Felipe Nasr and Marcus Ericsson.
Will Stevens and Roberto Merhi of Manor clocked the slowest times of qualifying.
