Ricciardo leads Red Bull 1-2 in Practice 1 in Monaco
DANIEL Ricciardo set a new lap record to lead teammate Max Verstappen in Monaco GP Practice One as Red Bull set an ominous early pace.
The Australian posted a 1:12.126 on F1 2018's new hypersoft tyres to beat the previous lap record of 1:12.178 which Kimi Raikkonen claimed pole with in 2017.
Verstappen was 0.154s off his teammate's time, although the Dutchman had a minor 'off' at St Devote and is under investigation by the stewards for failing to rejoin the track in a safe manner.
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"The car is working quite nicely but it is still only Thursday morning," Red Bull team principal Christian Horner told Sky Sports F1.
"We've had a competitive chassis all year and the straights are a bit shorter here so it concertinas all together."
World champion Lewis Hamilton was over three tenths off the leading Red Bull in third on the same tyres, with Vettel and Raikkonen a further half a second back in the Ferraris.
Carlos Sainz secured the early 'best of the rest' tag for Renault as he pipped the second Mercedes of Valtteri Bottas for sixth in the time sheet.
But it was a very difficult morning for McLaren and Haas as both teams suffered mechanical issues.
Fernando Alonso's MCL33 suffered a brake-by-wire issue after only five laps and while he managed to return to the track for the final eight minutes, the Spaniard finished 17th, two places behind Stoffel Vandoorne in the sister car.
Kevin Magnussen was slowest of all after his running was curtailed after under half an hour due to a connector issue on his Haas.
Romain Grosjean, arriving in Monte Carlo on the back of two crashes, also saw his session disrupted after he brushed the wall which required 50 minutes of repair work to his car.
However, the Frenchman put in some good laps late on to finish ninth, behind the Force India of Sergio Perez.
Sergey Sirotkin also hit the wall in the Williams, but the Russian recovered to squeeze into the top 10 and was over eight tenths quicker than teammate Lance Stroll.
Charles Leclerc, taking part in his home grand prix, was 16th but nearly four tenths quicker than Sauber teammate Marcus Ericsson.
Monaco GP Practice One Timesheet
Driver - Team - Time - Tyres
Daniel Ricciardo - Red Bull - 1:12.126 - Hypersofts
Max Verstappen - Red Bull - +0.154 - Hypersofts
Lewis Hamilton - Mercedes - +0.354 - Hypersofts
Sebastian Vettel - Ferrari - +0.915 - Hypersofts
Kimi Raikkonen - Ferrari - +0.940 - Hypersofts
Carlos Sainz - Renault - +1.330 - Hypersofts
Valtteri Bottas - Mercedes - +1.376 - Hypersofts
Sergio Perez - Force India - +1.591 - Hypersofts
Romain Grosjean - Haas - +1.817 - Hypersofts
Sergey Sirotkin - Williams - +1.836 - Hypersofts
Esteban Ocon - Force India - +1.874 - Hypersofts
Brendon Hartley - Toro Rosso - +1.908 - Ultrasofts
Nico Hulkenberg - Renault - +2.008 - Hypersofts
Pierre Gasly - Toro Rosso - +2.114 - Ultrasofts
Stoffel Vandoorne - McLaren - +2.165 - Hypersofts
Charles Leclerc - Sauber - +2.395 - Hypersofts
Fernando Alonso - McLaren - +2.511 - Hypersofts
Lance Stroll - Williams - +2.656 - Hypersofts
Marcus Ericsson - Sauber - +3.080 - Hypersofts
Kevin Magnussen - Haas - +6.675 - Ultrasofts