Daniel Ricciardo continued his and Red Bull's Monaco Grand Prix dominance as he again led the way in Saturday's final practice session, while team-mate Max Verstappen crashed out.
Ricciardo posted a time of 1:11.786, with his lap coming shortly after Verstappen hit the wall exiting Piscine, giving Red Bull a repair job over the lunch break.
Ferrari emerged as Red Bull's primary challenger as Sebastian Vettel and Kimi Raikkonen took third and fourth.
Mercedes, meanwhile, was fifth and sixth with Lewis Hamilton leading their charge on a 1:12.273, almost half a second down on Ricciardo's record lap time. Bottas endured a scruffy session which saw him run off the circuit and clatter the barrier with his rear-wing. The Finn then blocked Verstappen on one of his runs.
Toro Rosso vaulted up the order to finish as the midfield leader, with Brendon Hartley and Pierre Gasly seventh and eighth, providing hope that the team can return to Q3 this afternoon.
Carlos Sainz Jr. was ninth for Renault while Sergey Sirotkin caught the eye as he completed the top 10 for Williams, edging out McLaren's Stoffel Vandoorne, and eight-tenths clear of team-mate Lance Stroll.
Force India duo Esteban Ocon and Sergio Perez were 12th and 13th ahead of Nico Hulkenberg and Fernando Alonso.
Home representative Charles Leclerc took 17th, while Haas' struggles continued as Kevin Magnussen and Romain Grosjean (who heads into qualifying with a three-place grid penalty) finished ahead of only Marcus Ericsson.
